Constructs

The improvement in measurement effectiveness achieved by ML-guided adaptive experimentation compared to conventional static measurement protocols. For XRD, this means using early diffraction data to steer subsequent measurements toward informative angular ranges.

A double-ion exchange synthesis strategy where two anions are simultaneously exchanged between precursors, enabling formation of complex oxides at substantially lower temperatures than conventional ceramic routes by providing large thermodynamic driving forces.

Binary indicator: 1 if Polity IV score is between -5 and +5, indicating a mixed or incoherent regime type. Anocracies are predicted to have higher conflict risk than either full democracies or full autocracies (inverted-U).

Mixed regime type (Polity score approximately -5 to +5) that combines elements of democracy and autocracy. Anocracies face elevated coup risk compared to both full democracies and consolidated autocracies — the 'inverted U' hypothesis. Partial liberalization creates political competition without establishing strong civilian control institutions.

Contemporary framing of military coups as anti-neocolonial liberation, particularly in Francophone Africa. The 2020-2023 Sahel coup wave featured explicit anti-French rhetoric, expulsion of French military forces, and pivot toward Russia/Wagner Group. This framing generates popular legitimacy and complicates international anti-coup responses by reframing coups as sovereignty assertions.

The international normative prohibition against unconstitutional changes of government that emerged after the Cold War. Institutionalized through AU Lomé Declaration (2000), OAS Inter-American Democratic Charter (2001), and UN General Assembly resolutions. Tansey (2017) documents the norm's rise and argues it has meaningfully reduced coup frequency post-1991. However, Tansey also warns of 'norm fading' as recent coups (2020s Sahel wave) face weaker international responses.

International normative prohibition against mercenary activity, codified in the 1989 UN Mercenary Convention and the OAU Convention. Petersohn (2014) argues PMSCs achieved legitimacy by reframing their use of force as 'individual self-defence' rather than combat participation, effectively circumventing the norm without directly violating it.

Degree to which production of active pharmaceutical ingredients is concentrated in a small number of countries. China and India produce approximately 80% of global APIs, creating structural vulnerability in pharmaceutical supply chains.

African Union's institutional response to unconstitutional changes of government: automatic suspension of membership under the Lome Declaration (2000) and Addis Ababa Charter. Souare (2014) finds the AU norm had partial deterrent effects but enforcement is inconsistent, particularly when coups enjoy popular support or major power backing.

The probability that tax underreporting is detected in a given audit, estimated from random audit programs. Decomposed by income source: third-party reported income (near-zero evasion detected) vs. self-reported income (substantial evasion). A key parameter in optimal deterrence models of tax compliance.

Categorical classification of autocratic regimes following Geddes, Wright & Frantz (2014): military, single-party, personalist, and monarchy. Each type has distinct coup risk profiles. Military regimes face the highest coup risk (intra-military factionalism), personalist regimes face moderate risk (concentrated power but coup-proofing degradation), party regimes face lowest risk (institutionalized power-sharing), and monarchies have intermediate risk.

An illegal seizure or extension of power by a sitting executive who dissolves or suspends the legislature, judiciary, or constitution to consolidate personal rule. Distinguished from classic military coups by the perpetrator being the incumbent. Examples include Fujimori in Peru (1992), Maduro in Venezuela, and contemporary executive aggrandizement. Increasingly common in the post-Cold War period as classical military coups decline.

ML-based methods for automatically identifying crystalline phases from X-ray diffraction data, including probabilistic neural networks and adaptive measurement strategies that optimize data collection for phase detection.

The energy difference between the valence band maximum and conduction band minimum in a crystalline material, measured in eV via DFT (PBE functional). Determines whether a material is metallic (0 eV), semiconducting, or insulating. A key target in Matbench regression tasks.

The ratio of marginal likelihoods of two competing models, BF12 = p(data | M1) / p(data | M2). Quantifies the evidence the data provide for one model over another, updating prior model odds to posterior model odds. Kass & Raftery (1995) propose conventional thresholds (BF > 3 substantial, > 10 strong, > 100 decisive). Sensitive to prior specification; used cautiously in modern workflow.

Linear regression in which coefficients and error variance are treated as random variables with prior distributions, yielding full posterior distributions over parameters and predictions rather than point estimates. With conjugate Normal-Inverse-Gamma priors the posterior is available in closed form; otherwise it is obtained via MCMC or variational inference.

Categorical sentiment label assigned to a 256-token chunk of a Federal Reserve Beige Book report, taking values in {negative, mixed, positive}. Derived from human annotations on a -1 to 1 scale, with [-1, -0.2) = negative, [-0.2, 0.2] = mixed, (0.2, 1] = positive.

Beta measures a security's sensitivity to market-wide movements. CAPM decomposes total risk into systematic (beta, compensated) and idiosyncratic (diversifiable, uncompensated) components.

A topological descriptor derived from persistent homology applied to electron density fields of crystalline solids, encoding bonding characteristics by tracking topological features (connected components, loops, voids) across varying density thresholds as a function of filtration parameter.

Geographic distance in kilometers between two trading countries' economic centers; standard control variable in gravity models of trade.

The monetary value of goods and services traded between a pair of countries in a given period; outcome variable in gravity models.

Total value of exports and imports between origin and destination countries, hypothesized to be amplified by migrant networks.

Mean live-birth weight in origin households or communities, used as a proxy for prenatal nutrition and population health.

Private security services provided by Chinese state-owned enterprises and private security companies to protect Belt and Road Initiative investments and personnel abroad. Represents an emerging model where security companies may evolve from asset protection to security force assistance and training.

A material's resistance to uniform compression, defined as the ratio of an infinitesimal pressure increase to the resulting relative volume decrease; a structure-dependent mechanical property predicted by ML models.

Phenomenon where demand variability amplifies as it propagates upstream through supply chain echelons. Small fluctuations in consumer demand produce increasingly large swings in orders placed by upstream suppliers.

O'Donnell's (1973) model for Latin American military regimes where coups are executed by the military as an institution (not individual officers) in alliance with technocratic elites to impose economic modernization. Characterized by exclusion of popular sectors, technocratic economic management, and institutional rather than personalist military rule.

The average electrochemical potential for reversible Ca2+ insertion/extraction in a host cathode material for Ca-ion batteries. Higher voltages enable higher energy density.

The activation energy for Ca2+ migration in solid-state materials, critical for both Ca-ion battery cathodes and solid electrolytes. Ca2+ mobility is generally much lower than Li+ due to its larger size and higher charge density.

The statutory rate applied to realized gains from the sale of assets held beyond a specified period (typically long-term). Affects savings behavior, portfolio allocation, and lock-in effects. Varies substantially across countries and asset types.

Number or proportion of supply chain nodes rendered non-functional following an initial disruption, measuring the extent of downstream propagation through the network.

The directional control in programmable catalytic loops where dynamic oscillations in catalyst composition or surface state drive net reaction progress in a preferred direction. A key concept in catalytic resonance theory — the frequency and amplitude of oscillations determine whether the catalytic cycle runs forward, backward, or reaches a dynamic steady state.

The optimal oscillation frequency at which forced dynamic modulation of a programmable catalyst achieves maximum rate enhancement, determined by the match between external forcing period and intrinsic catalytic turnover timescales.

The gravimetric charge storage capacity of a battery cathode material (mAh/g). Determined by the number of intercalatable ions per formula unit and the molecular weight. Higher capacity enables higher energy density batteries. Theoretical capacity from DFT; practical capacity from electrochemical cycling.

The energy difference (eV/atom) between the fully ordered and disordered cation arrangements in a mixed-metal oxide. In rocksalt cathodes, partial cation disorder can enable percolating Li diffusion pathways while maintaining structural stability. Computed via special quasi-random structures (SQS) or cluster expansion.

A mechanism for thermochemical water splitting where cation vacancies in spinel metal oxides (rather than conventional oxygen vacancies) mediate the redox cycling, enabled by cation site inversion that lowers vacancy formation energies.

The thermodynamic stability of perovskites with chalcogenide anions (S2-, Se2-, Te2-) instead of oxide or halide anions. These materials are scarce despite favorable tolerance factors, suggesting additional instability mechanisms.

Machine learning interatomic potentials that incorporate charge/oxidation state information (e.g., via magnetic moment prediction) to describe both atomic and electronic degrees of freedom, enabling modeling of redox-coupled phenomena in electrochemical systems.

The thermodynamic feasibility of a redox-active material to mediate chemical looping processes, assessed through equilibrium analysis of oxidation and reduction half-cycles under process-relevant conditions.

Share of children below the working-age threshold engaged in economic labor in the origin community. Often rises when household income shocks (e.g., loss of a migration earnings opportunity) force adjustment.

Number and scale of Chinese private security companies operating internationally, primarily to protect Belt and Road Initiative investments. Arduino (2020) estimates 35,000-62,000 Chinese security contractors in 50 African countries.

Exposure of supply chain logistics to disruption at critical maritime chokepoints (Suez Canal, Strait of Malacca, Panama Canal, Strait of Hormuz, Bab el-Mandeb). Approximately 80% of global trade by volume transits through these narrow passages.

Corporate income tax revenue lost to base erosion and profit shifting (BEPS) activities by multinational enterprises, expressed as a percentage of total CIT revenues or GDP. Quantifies the fiscal cost of tax competition and inadequate international coordination.

Time from civil war onset to termination, modeled in a Cox proportional-hazards framework where the hazard is the conditional probability of war termination given survival to time t. Used in the replication of Akcinaroglu & Radziszewski (2013) on African civil wars 1990–2008.

Binary indicator: 1 if a civil war began in this country-year, 0 otherwise. Fearon & Laitin define civil wars as internal conflicts with organized violence, at least 1,000 battle deaths, and effective resistance by both sides.

Violence against civilians perpetrated by or attributable to PMSC operations. Penel & Petersohn (2022) use CMAD to test the 'outsourcing atrocities' hypothesis across four world regions. Distinguished from general civilian casualties in conflict.

Measure of supply chain vulnerability to climate change impacts including extreme weather events, sea level rise, water scarcity, and temperature extremes affecting production and logistics.

Composite of reaction time (PVT), working memory (n-back), executive function (Stroop), and decision quality measured after controlled sleep restriction. Performance declines are cumulative: 6h/night for 14 days produces impairment equivalent to 48 hours total sleep deprivation. Crucially, subjective sleepiness plateaus after ~3 days while objective impairment continues to worsen.

Binary indicator for the Cold War period (pre-1991). Coup rates were substantially higher during the Cold War when superpower competition created permissive environments for military intervention. Post-Cold War democratic norms, international organizations, and conditional aid reduced the international tolerance for coups. Structural break in coup patterns around 1991.

Length of armed conflict in years from onset to termination. Key dependent variable in survival analysis of PMSC effects. Akcinaroglu & Radziszewski (2013) find competitive PMSC markets shorten conflicts; Petersohn (2024) finds early CMA intervention increases termination probability.

A bounded internal armed conflict between a government and one or more organized armed opposition groups, with a defined onset year and (eventual) termination year. The unit of analysis at which PMSC competition and government-event counts are aggregated for the duration replication.

Ordinal scale of battle-death intensity for a conflict-year, distinguishing minor conflicts from wars based on annual fatality thresholds. Used in AR2013 as a control for the severity of fighting, which may independently predict war termination.

Battle deaths per conflict-year as a measure of how violent an armed conflict is. Commonly operationalized using UCDP best estimates (bd_best). The 25 battle-death threshold distinguishes minor armed conflicts from wars.

Initiation of armed conflict as defined by UCDP (25+ battle deaths in a year). Petersohn (2021) finds PMSC presence in year t-1 is associated with subsequent conflict onset, suggesting PMSCs may anticipate or contribute to conflict initiation rather than being purely reactive.

Binary failure-event indicator for survival analysis: 1 in the conflict-year a civil war ends (peace, military victory, or low-activity threshold crossing), 0 otherwise. The dependent failure variable in the Cox proportional-hazards model of civil war duration.

A prior distribution that, when combined with a given likelihood, yields a posterior in the same parametric family. Enables closed-form posterior updates (e.g. Beta-Binomial, Normal-Normal, Gamma-Poisson) and is the basis for analytically tractable Bayesian models.

U.S. Consumer Price Index measuring aggregate price-level changes; used as an inflation outcome variable.

Coups require solving a collective action problem among military officers: each potential participant must believe enough others will also participate for the coup to succeed. The coordination challenge creates a focal point dynamic where information cascades (e.g., seizure of radio stations, public declarations) serve to coordinate expectations rather than provide military advantage. Singh (2014) shows coups succeed or fail primarily based on whether the initial movers can establish a focal point for coordination.

Numeric country code from the Correlates of War (COW) Project, version 4.1. Identifies a sovereign state or internationally-recognized political entity with a unique integer. Non-state entities and dependencies carry the sentinel value -999.

Numeric country code from the Gleditsch-Ward (G&W) state system, where it diverges from COW. Most countries share codes; this field captures divergences. NULL means G&W uses the same code as COW. Note: the Thyne do-file encodes most G&W divergences as year-conditional ccode remaps rather than country-name remaps; those time-varying rules are documented in EDGE_CASES.md.

ISO 3166-1 alpha-3 three-letter country code (e.g., 'USA', 'NGA', 'COL'). Best-effort enrichment derived by mapping COW numeric codes to ISO3 via a static lookup table. NOT authoritative — intended only as a convenience join key for PSED-era datasets (Africa, Latin America, Southeast Asia, 1990–2012). Countries outside that scope may have NULL or incorrect ISO3 values.

Numeric country code from the Polity IV/V project, where it diverges from the COW coding. Most countries share a COW and Polity code; this field captures the subset where they differ. NULL means Polity uses the same code as COW.

A country name string as it appears in a source dataset — including alternate spellings, historical names, abbreviations, article variants (e.g., 'The Bahamas' vs. 'Bahamas, The'), and transliteration variants. The crosswalk maps each variant to standardized numeric codes.

Binary indicator: an illegal and overt attempt by the military or other elites within the state apparatus to unseat the sitting executive. Following Powell & Thyne (2011), includes both successful and failed attempts. Excludes popular revolutions, civil wars, and foreign invasions unless led by domestic military/elite actors.

Regional diffusion or demonstration effects whereby coups in neighboring or culturally similar states increase coup risk domestically. Mechanisms include: (1) demonstration that coups are feasible, (2) diffusion of coup-facilitating networks among military officers trained together, (3) regional instability creating permissive international environments. Operationalized as count of coups in neighboring states or regional coup rate.

Model-generated probability of a coup attempt occurring in a given country-year. Produced by statistical or machine learning models using structural, institutional, and contextual predictors. Examples include PITF models, ViEWS system (Hegre et al. 2019), and various logistic regression/random forest approaches in the literature.

Count or recency of prior coup attempts in a country. The single strongest predictor of future coups — the 'coup trap' dynamic where initial coups lower the normative and practical barriers to subsequent attempts. Countries with recent coup histories face 3-5x higher coup risk than countries without. Operationalized as binary (any prior coup), count, or years since last coup.

Binary indicator: a coup attempt that successfully results in the displacement of the incumbent chief executive and seizure of executive power for at least 7 days. Subset of coup_attempt. Success rate globally ~50% across 1950-2010 period.

The endogenous feedback loop where initial coups lower normative and practical barriers to subsequent attempts, creating a self-reinforcing cycle. Mechanisms include: (1) normalization of military intervention, (2) weakening of civilian institutions, (3) demonstrated feasibility reducing coordination costs, (4) economic damage from instability further increasing grievances. First articulated by Londregan & Poole (1990). Countries in the coup trap face 3-5x higher risk than those without coup history.

Categorical classification of coup events by agent and mechanism: military coup (institutional military seizure), palace coup (insider elite replacement), self-coup/autogolpe (incumbent dissolves constraints), counter-coup (reversal of previous coup), popular/democratic coup (military acts with popular support against incumbent). Different types have distinct structural preconditions, success rates, and post-coup trajectories.

An interval containing a specified probability mass of the posterior distribution (e.g. the central 95% credible interval). Unlike a frequentist confidence interval, it admits the direct probabilistic interpretation that the parameter lies within the interval with the stated probability, conditional on the model and data.

Degree of reliance on geographically concentrated or scarce mineral inputs essential for production. High dependency on minerals with concentrated extraction/refining (e.g., cobalt, rare earths, lithium) creates structural vulnerability.

A graph-based encoding of crystal structures where atoms are nodes and bonds are edges, with node/edge features encoding atomic properties and interatomic distances. Used as input to graph neural network models (CGCNN, MEGNet, SchNet, DimeNet) for property prediction. The choice of graph construction (cutoff radius, edge features) significantly affects model performance.

The mathematical encoding of a crystalline material for ML input. Ranges from composition-only vectors (element fractions) to graph-based representations (atoms as nodes, bonds as edges with distances/angles). Graph representations enable equivariant GNNs; compositional features enable tabular ML (CGCNN, MEGNet, MACE vs. Magpie, SOAP).

Vulnerability of digital supply chain infrastructure to cyber attacks including ransomware, data breaches, IoT compromise, and third-party software vulnerabilities.

The enthalpy change associated with a compound decomposing into competing phases (other compounds and/or elemental forms). Unlike formation enthalpy which measures stability relative to elements only, decomposition enthalpy captures the true thermodynamic competition that determines compound stability.

Assurance that defense system components are authentic, uncompromised, and sourced from trusted suppliers throughout the acquisition lifecycle. Encompasses anti-counterfeit measures, trusted foundry programs, and supply chain illumination.

The erosion of democratic oversight when security functions are privatized — confidentiality clauses, contractor legal ambiguity, and legislative exclusion combine to shield PMSCs from public accountability mechanisms that apply to uniformed forces.

Military coups against democratic governments specifically. Svolik (2014) shows young democracies are most vulnerable, with risk declining as democracies consolidate. Thyne and Powell (2014) distinguish coups against democracies (which typically reduce democratic quality) from coups against autocracies (which can promote democratization).

Population-driven stress: youth bulge (15-29 age cohort > 20% of population), rapid urbanization, food/water scarcity per capita, and disease burden. Youth bulges are robustly associated with conflict onset (Urdal 2006).

The accuracy of different density functional theory exchange-correlation approximations (PBE, SCAN, r2SCAN) for predicting thermodynamic properties of inorganic solids, including formation enthalpies and phase stability.

The accuracy with which density functional theory approximations (PBE, SCAN, r2SCAN) predict the thermodynamic stability of inorganic solids, measured as mean absolute error relative to experimental formation enthalpies.

Stock of co-nationals resident in a destination country (or globally), often weighted by skill. Mediates trade, FDI, and knowledge flows back to origin.

The ratio of a model's precision at top-k screening relative to random selection baseline. Quantifies how much faster a model identifies stable materials compared to untargeted DFT calculation. A DAF of 6 means 6x more discoveries per DFT calculation than random. Primary efficiency metric in Matbench Discovery.

Finer's (1962) two-condition model: military intervention requires both disposition (motive to intervene) and opportunity (capacity and permissive environment). Disposition comes from corporate grievances, political ideology, or ethnic/class interests. Opportunity from weak civilian institutions, regime crisis, or external support.

Composite measure of disruption impact capturing magnitude of operational, financial, and reputational consequences. Integrates revenue loss, recovery time, and downstream propagation extent.

The electronic band gap of inorganic halide double perovskites (A2BB'X6), which determines their suitability for optoelectronic applications. Computed via hybrid DFT (HSE06) or GW-BSE methods.

The extent of fluorine incorporation into disordered rocksalt cathode materials, which modifies voltage, capacity, and Li percolation. Achieving target fluorination requires careful precursor selection to avoid LiF formation.

Post-Earnings Announcement Drift (PEAD) — the tendency for stock prices to continue drifting in the direction of an earnings surprise for weeks after announcement. One of the strongest violations of semi-strong EMH.

Rate of increase in a country's GDP or GDP per capita over time, the standard measure of macroeconomic performance.

Short-term negative deviation in GDP growth rate, typically measured as annual real GDP growth or growth relative to trend. Sudden economic downturns increase coup risk by creating popular discontent, weakening regime legitimacy, and reducing the regime's ability to buy military loyalty through patronage.

Capacity of a state economy to absorb and recover from shocks — measured by GDP volatility, fiscal space (debt-to-GDP), foreign reserves, and export diversification. Low resilience states are coup-prone and food-crisis-prone.

Taxes actually paid by corporations as a proportion of pre-tax accounting profits, measured at the firm or aggregate level. Incorporates deductions, depreciation allowances, credits, and tax planning, typically well below the statutory rate.

An estimate of the number of independent samples an autocorrelated MCMC chain is equivalent to, computed from the chain's autocorrelation function. The primary diagnostic for determining whether a chain has sampled the posterior adequately; ESS < ~400 for quantities of interest typically indicates insufficient sampling.

Total taxes paid as a share of pre-tax income, computed separately for each income quintile; measures progressivity of the tax system.

Average effective tax rate (taxes paid / pre-tax income) computed separately for each income quintile of the population. Captures the full distributional incidence of the tax system across the income distribution, combining income, payroll, consumption, and other taxes.

The percentage change in reported taxable income in response to a one-percent change in the net-of-tax rate (1 - marginal tax rate). Combines real labor supply responses with avoidance and evasion responses. A sufficient statistic for the welfare cost of income taxation under certain conditions (Feldstein 1999).

Observable indicators of elite fragmentation preceding coups: public criticism of the leader by senior officials, military commanders refusing orders, cabinet resignations, and shifts in state media tone. These signals are critical for both coup forecasting models and for regime insiders assessing coordination feasibility.

The removal of potential rivals from positions of power within the ruling coalition, particularly from military command positions. Sudduth (2017) shows that purges are strategically rational for dictators facing coup threats but create a 'purge paradox': the act of purging can trigger the very coup it aims to prevent if targets learn of impending purges and preemptively strike. Purges are most dangerous when they target officers with independent support bases.

The thermodynamic distance of a material from the convex hull of stable phases in compositional space, measured in eV/atom. Materials with e_above_hull = 0 are thermodynamically stable; positive values indicate metastability. The key stability criterion in high-throughput screening.

The energy difference (eV/atom) between a material and the convex hull of thermodynamically stable phases at the same composition. E_hull = 0 means the material is on the hull (thermodynamically stable). Positive values indicate metastability. The primary metric for assessing whether a computationally predicted material could exist.

Mean absolute error (meV/atom) of an ML model's predicted formation energy or total energy compared to DFT reference calculations. The primary accuracy benchmark for ML property prediction models. State-of-the-art models achieve ~20-30 meV/atom on Materials Project datasets.

Projected demand for minerals critical to clean energy technologies (lithium, cobalt, nickel, rare earths, copper, graphite) driven by EV batteries, wind turbines, solar panels, and grid storage.

The excess expected return of equity investments over a risk-free benchmark; central premium in factor-pricing models.

Natural log of the ethno-linguistic fractionalization (ELF) index, measuring the probability that two randomly selected individuals in a country belong to different ethnic groups. Higher values indicate greater ethnic diversity; included as a control in the AR2013 duration model.

The degree to which the ethnic composition of the military (especially officer corps) diverges from the general population. Ethnic homogeneity in the military (via ethnic stacking) may increase loyalty to the regime but creates grievances among excluded groups that can fuel civil war (Roessler 2011, Harkness 2014).

The deliberate appointment of co-ethnics or loyalists to key command positions in the military and security forces. A form of coup-proofing that increases short-term regime security by ensuring military leaders share identity-based loyalty with the ruler, but creates long-term instability by generating grievances among excluded ethnic groups and degrading meritocratic military performance (Harkness 2014, Roessler 2011).

Binary indicator equal to 1 if the civil conflict has a predominantly ethnic character, 0 otherwise. Included in the AR2013 model as a control because ethnic conflicts may follow different termination dynamics than non-ethnic ones.

The energy required to dissociate an electron-hole pair (exciton) in a semiconductor. In double perovskites, large exciton binding energies indicate strong electron-hole coupling, relevant for light-emitting applications.

Incremental incumbent-led erosion of democratic checks and balances (e.g., judicial independence, legislative oversight, press freedom) through legal and institutional changes; a non-coup pathway to autocratization.

Degree of foreign involvement in state affairs — military intervention, peacekeeping presence, foreign aid dependency (ODA as % of GNI), and sanctions. High external intervention signals inability to self-govern and can entrench fragility.

Presence and scale of mining, oil, gas, or other resource extraction operations in a country or conflict zone. Creates demand for private security services to protect investments and personnel, particularly in weak-state environments.

Fragile States Index sub-indicator: elite competition, power-sharing breakdown, defections, and brinksmanship. Factionalized elites are a proximate trigger for coups, civil war, and state collapse.

A security's loading on systematic risk factors that explain cross-sectional return variation. Fama-French 3-factor model includes market, size (SMB), and value (HML). Five-factor model adds profitability (RMW) and investment (CMA). Factor alpha is return unexplained by factor exposures.

Total fertility rate (children per woman) at origin, hypothesized to respond to migrant-transmitted reproductive-health norms.

Binary indicator of whether a model received additional pre-training and supervised fine-tuning on domain-specific (Beige Book) text and labels, beyond general pre-training.

Rate of new firm formation in the origin economy, hypothesized to be sensitive to skilled emigration.

Difference between government revenue and expenditure as a percentage of GDP, where negative values indicate budget deficits and positive values indicate surpluses

Interruption in the production, processing, distribution, or retail of food products causing shortages, price spikes, or food safety incidents. Includes agricultural production failures, logistics disruptions, and processing facility closures.

Mean absolute error (eV/Å) of an ML interatomic potential's predicted atomic forces compared to DFT reference calculations. The primary accuracy benchmark for neural network potentials. CHGNet achieves ~30 meV/Å on MPtrj test set; lower values indicate more accurate molecular dynamics trajectories.

Area under the ROC curve for coup prediction models. Most published models achieve AUC of 0.75-0.85 but with high false positive rates given the low base rate. Ward et al. (2010) argue that in-sample statistical significance is insufficient and out-of-sample predictive accuracy should be the standard for evaluating coup models.

Stock or flow of foreign direct investment from destination countries to the migrant's country of origin.

External military assistance (arms transfers, training, financial support) provided to a state's armed forces. Theoretically ambiguous effect on coup risk: may professionalize the military and increase civilian control, but may also empower the military and create dependencies that make aid withdrawal destabilizing. Cold War-era aid was often coup-permissive.

External military education and training programs (e.g., US IMET, French cooperation militaire). Savage and Caverley (2017) find foreign military training can increase coup risk by exposing officers to political ideas, building cross-national networks, and enhancing organizational capacity independent of the regime.

The energy released or required to form a crystal from its constituent elements in their standard reference states, normalized by the number of atoms. Measured in eV/atom via DFT calculations. The primary regression target in materials property prediction benchmarks.

Estimated annual GDP loss from workforce sleep deprivation through three channels: mortality (shorter lifespan), absenteeism (more sick days), and presenteeism (reduced on-the-job productivity). Hafner et al. (2017) estimate: US loses $411B/year (2.28% GDP), Japan $138B (2.92% GDP), UK $50B (1.86% GDP). Calculated via human capital approach.

Monthly estimate of the real GDP growth rate from the Brave-Butters-Kelley index, used because official GDP is published only quarterly.

Natural log of GDP per capita for the country in a given conflict-year, used as a control for economic development in the AR2013 Cox proportional-hazards model of civil war duration. Wealthier states are expected to have greater capacity to terminate conflicts quickly.

Logged real GDP per capita as a structural predictor of coup risk. Lower income levels are robustly associated with higher coup probability — the 'coup trap' mechanism where poverty creates grievances and lowers opportunity costs of plotting. One of the most robust predictors across studies (Londregan & Poole 1990, Gassebner et al. 2016).

Shift toward more egalitarian household decision-making, female autonomy, and support for gender equity, hypothesized as a downstream effect of migration to liberal destinations.

AI models (diffusion models, variational autoencoders, large language models) that generate novel crystal structures. Benchmarked against baseline methods like random charge-balanced prototype enumeration and data-driven ion exchange of known compounds.

Degree to which supply chain nodes are spatially concentrated in a limited number of geographic regions, increasing vulnerability to localized disruptions (natural disasters, geopolitical events, pandemics).

Measure of geopolitical instability and policy uncertainty affecting supply chain operations, including sanctions, trade wars, armed conflicts, and regime changes.

A physically motivated descriptor identified via SISSO (sure independence screening and sparsifying operator) that predicts the Gibbs free energy of inorganic crystalline solids as a function of temperature, enabling temperature-dependent phase stability calculations with ~50 meV/atom accuracy.

Index from 0 to 1 measuring the degree of inequality in national income distribution where 0 is perfect equality

A machine-learned force field that maps crystal graph inputs to total energies, atomic forces, and stresses using message-passing neural networks. Trained on DFT trajectories (e.g., MPtrj ~1.6M structures), enabling geometry optimization at DFT accuracy but orders of magnitude faster. Examples: M3GNet, CHGNet, MACE-MP, SevenNet.

The classical geometric tolerance factor t = (r_A + r_X) / sqrt(2)(r_B + r_X) proposed by Goldschmidt (1926) for predicting perovskite stability. Values near 1.0 favor cubic perovskite; t < 0.8 or t > 1.0 favor non-perovskite structures. Achieves ~74% accuracy, superseded by Bartel's revised tau.

Total government spending including consumption and investment as a percentage of gross domestic product, measuring the size of government in the economy

Fragile States Index sub-indicator: ethnic, religious, or communal tensions and violence, including historical atrocities and discrimination. Captures the mobilizable resentment that can be weaponized for conflict.

NY Federal Reserve composite index measuring global supply chain conditions using transportation costs and manufacturing indicators. Positive values indicate above-normal pressure; negative values indicate below-normal conditions.

A coup in which the military intervenes claiming to safeguard the constitution or restore order, typically promising a return to civilian rule after a transitional period.

The electronic band gap (eV) of halide perovskite materials (ABX3 where X = Cl, Br, I). Critical for optoelectronic applications — optimal solar cell performance requires band gaps of 1.1-1.7 eV. Tunable via composition engineering of A, B, and X sites.

An MCMC algorithm that uses gradient information from the log-posterior to simulate Hamiltonian dynamics, producing long-range proposals with high acceptance rates. Scales substantially better than random-walk Metropolis in moderate-to-high dimensions and is the inference engine underlying Stan and PyMC.

A Bayesian model in which parameters are nested within higher-level distributions — e.g. group-level coefficients drawn from a shared population distribution. Enables partial pooling: estimates for data-poor groups are shrunk toward the population mean, reducing variance with controlled bias. Foundational for analyses with clustered, longitudinal, or cross-nested data structures.

Percentage of a country's high-skilled (tertiary-educated, professional, or top-academic) population currently residing abroad. Used by Batista et al. to characterize cross-country variation in skilled outflows; rates can exceed 50% for top academics and >90% for PhD holders in small/poor countries.

The fraction of computationally screened candidate materials that pass stability and property filters and are ultimately validated experimentally, reflecting the efficiency of computational materials discovery pipelines.

Share of households with effective access to health-care services, hypothesized to improve with remittance income.

Real income or consumption per capita in households or provinces at origin, sensitive to remittance and migration shocks.

Aggregate stock of skilled labor (e.g., licensed nurses, engineers, tertiary graduates) resident in the origin country at a given time. The central outcome of interest in the brain drain/gain debate.

Emigration of educated/skilled population and economic displacement. FSI sub-indicator capturing the loss of human capital that further degrades state capacity and economic prospects.

The market's forward-looking estimate of a security's volatility, extracted from options prices via Black-Scholes. IV rank compares current IV to its 52-week range. High IV rank favors premium-selling strategies; low IV rank favors buying options. VIX is the implied volatility of S&P 500 options.

Gini coefficient or other measures of income/wealth distribution as a predictor of coup risk. Higher inequality increases coup risk through two channels: (1) popular discontent creates a permissive environment for military intervention framed as corrective, (2) elites may sponsor coups to prevent redistributive policies. Houle (2016) finds inequality breeds coups but not civil wars, because coups require elite coordination while civil wars require mass mobilization.

Overall income distribution inequality within a population, measured by the Gini coefficient and related indices that capture the extent to which income deviates from a perfectly equal distribution.

Share of pre-tax national income accruing to the top 10 percent of earners in the income distribution

Proportion of total tax revenue derived from personal and corporate income taxes, indicating the progressivity and direct taxation reliance of the tax system

Deaths per 1,000 live births before age 1 in origin areas; key population-health outcome in brain-drain debates.

A prior distribution that encodes substantive knowledge from prior literature, expert elicitation, or previous studies — typically with concentrated mass around a non-default value. Used to formally incorporate accumulated evidence into new analyses; the core mechanism by which PAX knowledge-base findings can shape engine inference.

Government effectiveness and bureaucratic quality — the ability of the state to formulate and implement policy. Operationalized via WGI Government Effectiveness score or CPIA. Low capacity amplifies all other fragility drivers.

The average voltage (V) at which a guest ion (Li+, Mg2+, Ca2+) intercalates into or de-intercalates from a cathode host structure. Computed from DFT total energies of the charged and discharged states. A key performance metric for battery cathode materials — higher voltage means higher energy density.

Correlation between parent and child income rankings measuring the degree of social mobility across generations

Degree to which children's economic outcomes depend on their parents' income, reflecting equality of opportunity and the persistence of economic advantage across generations.

Economic sanctions, aid suspensions, and diplomatic isolation imposed in response to coups. Intended to deter coups and pressure coup regimes toward elections. Effectiveness is debated: Marinov and Goemans (2014) find post-Cold War sanctions push toward elections, but Tansey (2017) documents declining credibility of enforcement.

The ratio of safety stock to average demand, representing the degree of inventory-based buffering against supply chain variability.

Aggregate investor optimism or pessimism beyond what fundamentals justify. High sentiment inflates speculative stocks; low sentiment depresses them. Measured by Baker-Wurgler index, put/call ratios, fund flows, or survey measures.

The energy barrier governing the rate of ion exchange reactions in solid-state synthesis, determined by defect formation energies and hopping barriers in the salt precursor rather than the ceramic target material.

Total employee compensation as share of gross domestic product measuring the split between labor and capital

Output per worker in the origin economy, sensitive to skill outflows and to firm capital-labor substitution responses.

Coefficient of variation of actual delivery lead times relative to contracted/expected lead times. Higher variability indicates unreliable supply and amplifies bullwhip effects.

What happens to the deposed leader after a successful coup: exile, imprisonment, death, trial, or negotiated departure. Leader fate varies systematically by regime type and era. Post-Cold War deposed leaders are more likely to face exile or trial than death. Goemans, Gleditsch and Chiozza (2009) Archigos dataset tracks leader fate systematically.

Number of years the current chief executive has been in power. Non-linear relationship with coup risk: new leaders face high risk during consolidation period, risk declines as they establish control and patronage networks, but may rise again in very long tenures as succession anxieties emerge and loyalty networks calcify.

Fragile States Index sub-indicator: public confidence in state institutions, corruption perceptions, political participation restrictions, and regime contestation. States with large legitimacy deficits face elevated coup and revolution risk.

The activation energy barrier (eV) for Li-ion migration between adjacent sites in a cathode crystal structure. Computed via nudged elastic band (NEB) calculations. Lower barriers enable faster charge/discharge rates. Typically 0.2-1.0 eV for intercalation cathodes.

The degree to which asset prices fully reflect all available information. Fama's weak form (prices reflect past prices), semi-strong form (prices reflect all public info), and strong form (prices reflect all info including private). A central organizing concept in finance that defines whether systematic excess returns are possible.

The ease with which a security can be bought or sold without causing significant price impact. Measured by bid-ask spread, market depth, and trading volume. Low liquidity amplifies volatility and increases trading costs.

The study of trading mechanisms, order types, market makers, and how market design affects price formation and trading costs. Covers informed vs. uninformed trading, adverse selection, and the economics of market making.

A class of algorithms (Metropolis-Hastings, Gibbs sampling) that generate samples from an arbitrary target distribution — typically a Bayesian posterior — by constructing a Markov chain whose stationary distribution is the target. The dominant approach to approximate posterior inference when the posterior lacks a closed form.

The largest peak-to-trough decline in portfolio or security value over a given period. Measures tail risk and the psychological challenge of a strategy. Calmar ratio = annualized return / max drawdown.

Primary regression metric in Matbench: average absolute difference between predicted and DFT-computed material properties (eV/atom for energies, eV for band gaps, GPa for moduli). Lower is better; state-of-the-art models achieve ~0.02–0.05 eV/atom for formation energy.

The tendency for asset prices or returns to revert toward a long-run average after extreme moves. DeBondt and Thaler (1985) documented 3-5 year reversal in stock returns. Contrasts with short-term momentum. Basis of contrarian investing and pairs trading.

The ability to selectively synthesize a metastable crystal polymorph over the thermodynamically stable ground state through careful control of reaction energetics and surface energy contributions in solid-state synthesis.

The thermodynamic driving force available in metathesis (double displacement) reactions for inorganic synthesis, which can dramatically alter the reaction landscape to enable rapid and selective formation of target phases that are otherwise difficult to synthesize via traditional routes.

Binary assessment of whether a proposed metathesis (double exchange) reaction between two precursors will produce the desired product. Determined by comparing the thermodynamic driving force of the target reaction against all competing reaction pathways. A feasible metathesis reaction has negative ΔG and high selectivity.

The activation energy for Mg2+ ion hopping between sites in a host crystal structure, typically measured in meV. Lower barriers enable faster Mg-ion diffusion and better cathode rate capability in rechargeable Mg batteries.

The ionic conductivity of solid-state Mg2+ conductors, critical for enabling all-solid-state Mg batteries. Limited by the high migration barriers of divalent Mg2+ ions in most crystalline hosts.

Exogenous policy event in the destination country that changes the supply of visas or migration eligibility for citizens of an origin country. Provides identification variation in causal studies.

The degree to which the armed forces operate independently from civilian political control. High military autonomy — separate intelligence apparatus, independent budget authority, professional promotion criteria, corporate identity — increases both the capability and motivation for military intervention in politics. Reduced by coup-proofing but at the cost of military effectiveness.

Military-owned enterprises, commercial holdings, and economic stakes held by armed forces as an institution. Prominent in Egypt, Pakistan, Indonesia, and Myanmar. Creates a distinct coup motivation: protecting corporate economic interests rather than purely political or ideological goals. Military economic empires give the armed forces both motive and resources for political intervention.

Institutional interests of the armed forces as an organization: budget, autonomy, prestige, professional prerogatives. When civilian governments threaten military corporate interests (budget cuts, restructuring, accountability), coup risk increases. Distinct from individual officer grievances.

Sub-coup military insubordination that can escalate to full coups. Mutinies involve collective refusal of orders or localized military uprisings, often over pay, conditions, or grievances. Distinguished from coups by lacking intent to seize executive power, but mutinies can escalate or provide cover for coup attempts. The Mali 2012 coup began as a mutiny.

Huntington's triad of professional military attributes: corporate identity (the military as a distinct institution), expertise (management of violence), and responsibility (service to the state). Higher professionalism theoretically reduces coup risk by instilling norms of civilian supremacy. However, Böhmelt et al. (2018) find that military academies (a proxy for professionalism) can actually increase coup risk by creating networks and shared identity among officers.

Binary indicator that the current regime originated from a military coup or is led by active/former military officers. Military-origin regimes face distinctive coup dynamics: they are more vulnerable to coups from within the military institution (factional coups) but may have better intelligence on potential plotters. One of the most robust predictors of coup risk in the Gassebner et al. (2016) extreme bounds analysis.

Military expenditure as a percentage of GDP or total government expenditure. Has theoretically ambiguous effects on coup risk: higher spending may buy military loyalty and reduce grievances, but also empowers the military as an institution and increases its capacity to act. Empirical evidence is mixed (Gassebner et al. 2016).

Proportion of test-set chunks a model predicts as mixed minus the human-labelled base rate of mixed (41.5%). Positive values indicate overprediction of the mixed class.

Use of machine learning models to correct systematic errors in DFT-computed enthalpies of formation by learning error patterns from electronic structure features. Can reduce PBE errors from MAE ~195 meV/atom to ~80 meV/atom.

Machine learning models trained to predict formation energies of inorganic crystalline solids from compositional and structural features. Model accuracy depends critically on training data quality, diversity, and balance across chemical space.

Application of machine learning interatomic potentials (MLIPs) to compute surface phase diagrams, surface energies, and surface reconstructions at a fraction of the DFT cost while maintaining near-DFT accuracy.

Categorical label distinguishing the architectural family of a sentiment classifier: lexical/dictionary-based, pre-trained transformer LLM, or fine-tuned BERT-family transformer.

Wall-clock time required for a model to classify the 200-chunk test set, on a Windows 11 laptop with 32 GB RAM and 3.3 GHz CPU (no GPU), or remote server in the case of GPT-4o.

Adherence to the 2008 Montreux Document on pertinent international legal obligations for states related to PMSC operations during armed conflict. Signed by 54 states and 3 international organizations. Penel & Petersohn (2022) find Montreux-member governments show 72% reduced civilian victimization.

Global measure of spatial autocorrelation in trade flow or supply chain activity data. Positive values indicate geographic clustering of similar trade intensities; negative values indicate spatial dispersion.

Natural log of the percentage of a country's territory classified as mountainous, used as a control for geographic factors that facilitate rebel sanctuary and prolong civil wars. Higher values indicate more rugged terrain.

Technical indicators derived from price averages over different windows (SMA/EMA). Common signals include price crossing MA for trend entry, MA crossovers such as the golden cross, and distance from MA for mean reversion timing.

Degree to which a daytime nap (10-30 minutes) restores cognitive performance after sleep restriction. A 26-minute nap improves pilot performance by 34% and alertness by 54% (NASA nap study). However, naps do not fully compensate for chronic sleep debt — they provide temporary relief, not recovery. Longer naps (>30 min) risk sleep inertia.

A two-dimensional descriptor combining cation size and electronegativity differences to predict the thermodynamic stability of NASICON-structured materials (NaxMM'(PO4)3). Enables rapid screening of the large NASICON composition space.

Machine-learned tolerance factor for NASICON-structured materials based on Na content, elemental radii, electronegativities, and Madelung energy. Classifies NASICON phases in terms of their synthetic accessibility.

Strategic reconfiguration of supply chain geography by relocating production or sourcing closer to end markets, reducing geographic concentration risk and lead time variability at potential cost of efficiency.

McFate's (2014) thesis that the post-Cold War security environment resembles the medieval period, with multiple overlapping authorities, privatized violence, and non-state armed actors coexisting with weakened states. PMSCs are a key manifestation.

Measure of a node's importance in a supply network based on the fraction of shortest paths between all other node pairs that pass through it. High betweenness indicates a critical chokepoint whose failure would disrupt many supply relationships.

A machine learning model trained on DFT data that predicts atomic energies, forces, and stresses from atomic positions and species. Examples include CHGNet, M3GNet, MACE, and SchNet. Enables molecular dynamics and structure relaxation at near-DFT accuracy but orders of magnitude faster. CHGNet uniquely incorporates magnetic moments and charge states.

Binary indicator: 1 if the state became independent within the prior two years. New states face elevated conflict risk due to weak institutions, contested borders, and unresolved ethnic or regional claims.

The likelihood that an ABN3 composition will crystallize in the perovskite structure. Nitride perovskites are extremely rare compared to oxide/halide analogs due to challenging synthesis and stability requirements.

An adaptive extension of HMC that automatically selects the trajectory length by detecting when the simulated path starts to double back on itself, eliminating the need to hand-tune the number of leapfrog steps. The default sampler in Stan and a core driver of the modern Bayesian workflow's practicality.

Non-tax government revenues — including fees, fines, state enterprise dividends, property income, and grants — as a percentage of total government revenue. High non-tax shares may reduce fiscal accountability and tax compliance incentives by weakening the revenue-service provision link.

Binary indicator: 1 if the state has territory that is physically separated from the main territory (e.g., islands, exclaves). Noncontiguity creates zones where state capacity is lower and rebel control is easier to establish.

Huntington's (1957) model of civil-military relations where civilian control is achieved through military professionalization. The military develops a distinct corporate identity, professional expertise, and ethic of political neutrality. Maximizing military professionalism minimizes military intervention in politics. Contrasted with subjective civilian control (political alignment). The dominant theoretical framework in CMR scholarship, though empirically contested.

The ratio of B-site cation radius to X-site anion radius (μ = r_B/r_X) in ABX3 perovskites. Values between 0.44 and 0.90 generally support stable octahedral coordination. Used alongside tolerance factors for perovskite stability prediction.

Binary indicator: 1 if fuel exports exceeded one-third of export revenues. Oil states may face conflict due to prize capture incentives, weaker tax-based state institutions, or Dutch disease effects on state capacity.

Oil and natural resource rents as percentage of GDP, with conditional effects on coup risk. Nordvik (2018) finds oil both promotes and prevents coups: windfall revenues allow regimes to buy military loyalty (rentier peace), but oil price crashes destabilize patronage networks and trigger coups. Bell (2016) confirms the conditional relationship. Ross (2001, 2012) shows oil wealth can stabilize autocracies broadly but creates brittle regimes vulnerable to external price shocks.

Sensitivity measures for options prices: Delta (price sensitivity to underlying), Gamma (delta sensitivity), Theta (time decay), Vega (sensitivity to IV changes), Rho (sensitivity to interest rates). Essential for understanding options P&L and managing positions.

The excess potential (V) required above the thermodynamic minimum to drive the oxygen evolution reaction (OER) on a catalyst surface. Lower overpotential indicates a more active catalyst. Typically measured at 10 mA/cm² current density. A key metric for evaluating electrocatalysts for water splitting.

Statistical arbitrage strategy exploiting mean-reverting spread between two cointegrated securities. When spread diverges beyond historical norms (z-score above 2), trade converges it back. Common pairs: stocks in same sector, ETF vs. components.

The thermodynamic driving force for a reaction between a specific pair of solid precursors at their interface, used to predict which intermediate phases form first during solid-state synthesis of multicomponent ceramics.

A model for solid-state synthesis where phase evolution from multiple precursors proceeds as a sequence of interfacial reactions initiating between two phases at a time. The most reactive pairwise interface determines which non-equilibrium intermediate phases form.

Simultaneous supply-side disruption (facility closures, labor shortages, logistics breakdowns) and demand-side shock (panic buying, demand shifts, sector reallocation) caused by pandemic events. Creates unprecedented bullwhip amplification.

The creation of multiple, competing armed bodies (presidential guards, paramilitaries, intelligence agencies with arrest powers) with overlapping jurisdictions. A key coup-proofing mechanism that prevents any single military unit from accumulating enough power to execute a coup. Reduces coup risk but fragments the security apparatus and degrades conventional military effectiveness.

Number of patent applications or grants attributed to inventors resident in the origin country.

A regime's ability to buy military and elite loyalty through material distribution. Higher patronage capacity reduces coup risk by raising opportunity costs of plotting. Patronage collapse from commodity price crashes or aid withdrawal is a common proximate trigger.

Combined employer and employee mandatory social contribution rates as a percentage of gross wages, financing social insurance programs. A key component of the overall labor tax wedge that affects labor demand and supply decisions.

Duration of peace following conflict termination, measured as time until conflict recurrence. Underexplored in PMSC literature relative to conflict duration and intensity.

GDP per capita, typically logged and lagged one year. One of the strongest predictors of civil war onset: wealthier countries have lower risk, reflecting higher opportunity costs of rebellion and greater state capacity to deter it.

The DFT-calculated energy difference between a perovskite ABX3 compound and its most stable decomposition products (eV/atom). Negative values mean the perovskite is thermodynamically stable; positive values indicate it will spontaneously decompose. More physically rigorous than geometric tolerance factors.

Binary classification of whether an ABX3 composition forms a perovskite crystal structure (1) or not (0). Determined experimentally via XRD phase identification. The primary prediction target for tolerance factor models and ML classifiers in the perovskite design literature.

A topological data analysis method that characterizes the topology of electron density distributions in crystalline materials. Computes persistence diagrams from sublevel sets of the electron density field, capturing features like connected components, loops, and voids at multiple scales. Used to classify crystal structure types and predict material properties.

Whether an event includes a public allegation that a PMSC committed a human-rights abuse, and if so, the type of abuse alleged. Allegations are not the same as substantiated abuse; PSED records what is reported, not what is judicially proven.

The degree to which private military and security companies are subject to legal, political, and market-based oversight mechanisms. Avant (2005) identifies three accountability channels: contractual, market, and public/political. PMSCs exist in legal gray zones between military and civilian status.

Identity of the party hiring PMSC services: government (state), rebel group, international organization, corporation, or private individual. Client type shapes accountability dynamics, service provision, and conflict outcomes. The CMAD codes client identity for each contract.

Count of distinct PMSCs hired by the government or by rebels during a given conflict episode. Akcinaroglu & Radziszewski (2013) introduced this as a measure of market competition, theorizing that more PMSCs operating in a conflict implies reputational competition and faster goal accomplishment.

Count of discrete, dated, located events in which a PMSC was reported to be involved within a given unit (country-year, conflict-episode, region-year). PSED's primary unit of observation. Each event must satisfy two coding rules: (1) at least one PMSC is named or clearly identifiable in the source, and (2) the PMSC is involved in one of the seven event types (work, demonstration, riot, strike, violence, crime, plot).

Categorical classification of the kind of occurrence in which a PMSC was involved. Four categories (demonstration, riot, strike, violence) inherit from SCAD (Salehyan et al. 2012) with PSED-added modifiers; three categories (routine work, crime, plot) are PSED additions to capture non-contentious and non-violent PMSC activity.

Count of PSED events with a government client (local, national, or foreign), aggregated to the conflict-episode level. The replication's substitute for Akcinaroglu & Radziszewski's competition variable on the government side.

Degree of organizational connection between a PMSC and a state government, ranging from fully state-owned enterprises (e.g., Chinese SOE security companies) through government-contracted firms to fully independent market actors. One axis of McFate's (2014) two-dimensional typology.

The aggregate revenue or market value of the global private military and security company industry, typically measured in USD per year.

Level of competition among PMSCs operating within a conflict zone or market segment. Akcinaroglu & Radziszewski (2013, 2020) argue competition disciplines PMSC behavior and improves outcomes; Faulkner, Lambert & Powell (2019) critique the operationalization, showing co-presence does not equal competition.

Classification of PMSC market organization as collaborative, competitive, or rival (Petersohn 2015). Alternatively: neoliberal, hybrid, or racketeering market types (Dunigan & Petersohn 2015). Market structure shapes PMSC behavior and conflict outcomes.

The degree to which PMSC deployment improves the military capability of the hiring party. Dunigan (2011) identifies conditions under which PSC use yields positive or negative tactical/strategic outcomes. Petersohn (2017) shows effectiveness translates to increased conflict severity.

Health, psychological, and well-being outcomes for PMSC personnel deployed in conflict environments, including rates of PTSD, mental health disorders, physical injury, and access to care relative to military counterparts.

Binary indicator (0/1) of whether a private military or security company is active in a given conflict-year. The workhorse measure in quantitative PMSC research, though widely acknowledged as crude — service-type disaggregation consistently produces more nuanced findings.

Count of PSED events with a rebel client, aggregated to the country-year (or conflict-episode) level. Mirrors `pmsc_government_event_count` on the rebel side; together the pair operationalizes Avant & Neu's PSED substitution for AR2013's competition variable.

Range of services offered by a PMSC, from purely defensive security (site protection, convoy escort) through military consulting and training to direct participation in combat operations. The CMAD codes 11 service categories spanning logistics to frontline combat. One axis of McFate's (2014) typology.

Categorical classification of the service the PMSC performed during the event. Categories follow Avant 2005's taxonomy and span external (military-adjacent) and internal (security) support. The service observed may differ from what the PMSC was contracted for.

The Bourdieusian capacity of private military and security companies to shape shared understandings of legitimate security provision and what counts as security expertise.

Categorical classification of private military and security companies by organizational form and service portfolio. Singer (2003) distinguishes military provider firms, military consulting firms, and military support firms. McFate (2014) uses a 2-axis typology: government linkage (state-connected to independent) × service spectrum (security-only to military operations).

Quality of democratic institutions, electoral participation, and demand for public accountability at origin, hypothesized to be influenced by emigrant exposure to destination-country institutions.

Binary indicator: 1 if there was a three-or-more-point change in Polity score in the previous three years. Captures regime transitions and political turbulence that may lower the cost of civil war initiation.

Combined Polity IV score ranging from -10 (fully autocratic) to +10 (fully democratic), included in AR2013 as a control for regime type, which may affect the government's capacity and willingness to end conflicts through negotiation or force.

The degree to which a solid-state synthesis pathway preferentially forms one crystal polymorph over thermodynamically competing polymorphs, governed by the interplay of reaction energy, surface energy, and nucleation barriers.

The degree of public support, mobilization, or perceived justification for a coup attempt; signaled by mass protests, demonstrations, and approval polling.

Total population, logged and lagged one year. Larger populations increase civil war risk — more people means more potential recruits and more heterogeneous grievances, though the mechanism is contested.

Measure of shipping bottleneck severity at port facilities, reflecting vessel queue times, berth utilization, and container dwell times that constrain supply chain throughput.

The standard deviation of portfolio returns, driven by asset volatilities and pairwise correlations. Markowitz (1952) showed that combining low-correlation assets reduces portfolio risk below the weighted average of individual asset risks.

Probability that armed conflict resumes after termination. Bara & Kreutz (2022) argue PMSC presence exacerbates the credible commitment problem, making durable peace harder to achieve.

Onset of civil conflict following successful coups. Bell & Sudduth (2015) find coups during ongoing civil wars are common and alter war dynamics. Thyne (2015) shows coups increase the hazard of civil war onset. Roessler (2011, 2016) demonstrates the 'coup-civil war trap' in Africa where ethnic exclusion from the military trades coup risk for insurgency risk, creating an intractable dilemma.

Whether a successful coup leads to democratic transition within a defined period (typically 5-10 years). Marinov & Goemans (2014) find post-Cold War coups increasingly lead to competitive elections. Thyne & Powell (2014) show coups against autocracies are more likely to produce democratization than coups against democracies. Derpanopoulos et al. (2016) challenge this, finding coups rarely produce durable democracy. The debate remains active.

Whether competitive elections are held within a defined period after a successful coup. Marinov and Goemans (2014) find post-Cold War coups increasingly lead to elections, driven by international pressure and anti-coup norms. However, post-coup elections vary in quality and may legitimize military-backed candidates.

What regime type emerges after a successful coup: military junta, personalist dictatorship, transitional government leading to elections, or restored civilian rule. Geddes, Wright and Frantz (2014) show post-coup regime type varies systematically by the authoritarian regime type that was overthrown and by the Cold War vs post-Cold War period.

Changes in state repression and human rights practices following successful coups. Coup regimes frequently increase repression to consolidate power and deter counter-coups, particularly targeting the deposed leader's support base. The intensity and duration of post-coup repression varies by coup type and whether the coup faces domestic or international resistance.

The improvement in success rates achieved by passing ML-generated candidate materials through stability and property filters from pre-trained models (e.g., universal interatomic potentials) as a low-cost post-processing step.

Colonial-era military structures shaping post-independence coup risk. Colonial powers created ethnically segmented militaries, officer corps trained in metropolitan academies, and security forces designed for internal repression rather than external defense. Jenkins and Kposowa (1990, 1993) show these legacies explain significant variation in post-independence African coup rates.

The conditional distribution p(θ | data) of parameters given observed data, obtained by combining the prior and likelihood via Bayes' rule. Represents the full state of parameter uncertainty after observing evidence and is the primary output of Bayesian inference.

A model-adequacy diagnostic that simulates replicated datasets from the posterior predictive distribution and compares summary statistics (mean, variance, quantiles, test quantities) of the replications against the observed data. Systematic discrepancies indicate model misspecification. The standard goodness-of-fit procedure in the Bayesian workflow.

Percentage of population living below international poverty line of 2.15 dollars per day at purchasing power parity

Formal mechanisms in authoritarian regimes for distributing spoils and credibly committing to elites that they will receive ongoing benefits from cooperation: ruling parties, legislatures, cabinets, and patronage networks. Svolik (2009, 2012) shows these institutions reduce coup risk by solving the credible commitment problem — without them, the dictator cannot credibly promise not to eliminate rivals. Boix & Svolik (2013) demonstrate that power-sharing institutions are 'foundations of limited authoritarian government.'

A political system in which military intervention in politics is normalized and the armed forces act as the primary political arbiter. Coined by Perlmutter (1969/1977) and developed by Huntington (1968). Praetorian states lack effective civilian institutions to mediate political competition, making military intervention the default mechanism for regime change. Associated with weak party systems, low legitimacy, and fragmented civil society.

A computed score ranking candidate precursor combinations for solid-state synthesis of a target material. Incorporates thermodynamic driving force, selectivity against competing products, and practical considerations (melting point, reactivity, commercial availability). Higher scores indicate more favorable precursor choices.

The process by which markets aggregate dispersed information from buyers and sellers into a single observed price. Driven by informed trading, order flow, and arbitrage. Quality of price discovery affects how quickly prices reflect fundamental value.

The empirical tendency for securities with strong recent performance (typically 12-month return excluding the most recent month) to continue outperforming over the next 3-12 months. One of the most robust anomalies in finance — Jegadeesh and Titman (1993) documented roughly 1% per month excess returns to a long-short momentum strategy.

Feaver (2003) framework modeling civil-military relations as a principal-agent problem. Civilian principals delegate defense to military agents. Coups represent the ultimate form of agent rebellion when monitoring costs are high.

The volume of corporate profits artificially shifted from high-tax to low-tax jurisdictions by multinational enterprises, typically expressed as a percentage of global multinational profits or as corporate tax revenue loss. Estimated via comparison of reported profits with value-added-based profit shares.

The performance gain achieved by dynamically modulating catalyst surface binding energies through external forcing (voltage, strain, temperature oscillation), quantified as the ratio of dynamic to static catalytic rates or the reduction in required overpotential.

Natural log of the ratio of government military personnel to rebel force size, measuring the balance of military capability between sides. AR2013 includes this as a control because lopsided force ratios may accelerate conflict termination.

Mass protests and demonstrations as a short-term predictor and trigger of military coups. Casper & Tyson (2014) model popular protest as an information signal that helps military officers coordinate coup attempts by revealing the regime's weakness and reducing uncertainty about popular support for regime change. Johnson & Thyne (2018) find protests significantly predict coup attempts, especially anti-government protests that signal regime vulnerability.

The thermodynamic energetics of proton (H+) incorporation into perovskite and brownmillerite oxide structures, relevant for protonic ceramic fuel cells and electrochemical applications.

Total accumulated government debt as a percentage of gross domestic product, measuring the long-term fiscal sustainability and debt burden of the public sector

Deterioration in essential state services: health system capacity, education access, infrastructure maintenance, and social safety nets. Measured via FSI sub-indicator or composite of WDI health/education spending.

The ratio of put option volume to call option volume. High ratio signals bearish sentiment; low ratio signals bullish sentiment. Used as contrarian indicator — extreme readings can precede reversals. Equity P/C ratio below 0.5 or above 1.0 are notable extremes.

Residential separation of racial groups within geographic areas, reflecting patterns of housing discrimination, socioeconomic sorting, and historical exclusion.

King and Zeng (2001) rare events bias correction, critical for coup modeling where the base rate of coups is low (roughly 2-4% of country-years). Standard logistic regression underestimates the probability of rare events. Rare events logit, penalized likelihood, and Bayesian approaches address this. Affects both in-sample coefficient estimates and out-of-sample forecasting accuracy.

The Gibbs free energy change (ΔG, kJ/mol or eV/atom) of a solid-state synthesis reaction at a given temperature. More negative values indicate stronger thermodynamic favorability. Used to rank candidate synthesis pathways and predict whether a target material can be made via a particular precursor combination.

Quantitative metrics (primary and secondary competition) assessing the favorability of target phase formation versus impurity phase formation in solid-state reactions. Used to rank and select synthesis reactions that maximize target yield.

Duration required for a supply chain node to restore full operational capacity following a disruption. Central metric in the Simchi-Levi Risk Exposure Index framework.

The Reynolds-Smolensky index measures the reduction in income inequality due to the tax system, computed as the difference between the Gini coefficient of pre-tax and post-tax income. Separates vertical redistribution (progressivity × effective tax rate) from reranking effects.

Total forcibly displaced population (refugees + internally displaced persons) as count or per capita. Both cause and consequence of state fragility — displacement strains host communities, creates governance vacuums, and indicates state failure to protect.

Number of years since the last regime transition (3+ point Polity score change). Longer-lived regimes face lower coup risk due to institutional consolidation, established patronage networks, and routinized civil-military relations. New regimes are vulnerable during transition periods.

Geographic clustering and contagion of coup activity within a region, captured by neighbor-country coup history and shared regional norms about military intervention.

Strength of legal and institutional oversight mechanisms governing PMSC activity. Key instruments include the Montreux Document (2008), the International Code of Conduct for Private Security Providers (ICoC, 2010), national licensing regimes, and the ICoCA certification system.

A momentum oscillator measuring the speed and magnitude of price changes, ranging 0-100. RSI above 70 is conventionally overbought; below 30 is oversold. Useful for identifying momentum exhaustion, divergences, and entry/exit timing.

Probability that two randomly selected individuals belong to different religious groups (Herfindahl index). Ranges 0-1. Included as a control alongside ethnic fractionalization; not found to be a robust predictor of civil war onset.

Cross-border private transfers from migrants to households or institutions in the origin country. A major channel through which migration affects origin-country welfare.

States financed by external rents rather than taxation. Can buy military loyalty but are brittle when commodity prices crash.

Natural resource revenues (oil, gas, minerals, royalties) as a percentage of total government fiscal revenue. High dependence is associated with reduced tax effort, weakened state-citizen fiscal contracts, and vulnerability to commodity price volatility.

Migrants returning to their country of birth after working or studying abroad. Carries human capital, capital, and norms acquired in the destination back to the origin.

A geometric tolerance factor τ proposed by Bartel et al. (2019) that predicts whether a given ABX3 composition will form a stable perovskite structure. Unlike the classical Goldschmidt tolerance factor t, τ incorporates the oxidation state of A-site cation and uses a different functional form: τ = r_X/r_B - n_A(n_A - r_A/r_B / ln(r_A/r_B)). Achieves 92% accuracy on experimental perovskite/non-perovskite classification.

Disruption propagation through supply chain networks where a localized failure cascades downstream, affecting multiple tiers and functions. Distinguished from bullwhip by being disruption-driven rather than information-driven.

Quantitative measure comparing Time-To-Recover to Time-To-Survive for each supply chain node. Nodes where TTR > TTS represent critical vulnerabilities. Developed by Simchi-Levi et al. and implemented at Ford Motor Company.

The 2020-2023 cluster of military coups in the Sahel region: Mali (2020, 2021), Guinea (2021), Burkina Faso (2022), Niger (2023), Gabon (2023). Represents a potential structural break from the post-Cold War decline in coups. Characterized by anti-French/anti-Western framing, popular support, Wagner Group involvement, and weak international response. Tansey (2017) warned of 'anti-coup norm fading' before this wave materialized.

Number of distinct international co-authors or cross-border research collaborations per scholar.

Supply chain carbon footprint vulnerability — regulatory risk from emissions reporting requirements (EU CBAM, SEC climate disclosure) and transition risk from carbon pricing affecting supplier costs.

The practice of shifting capital between market sectors based on relative momentum, economic cycle positioning, or valuation. Tracked via sector ETFs. Strong relative momentum sectors are overweighted; weak sectors are underweighted.

Fragile States Index sub-indicator measuring internal security threats: state monopoly on force, politically motivated violence, arms proliferation, insurgency, and civil unrest. Higher values indicate greater security fragility.

Abrahamsen & Williams' (2009) theoretical framework describing how security governance operates through transnational networks blurring public/private distinctions. PMSCs, state forces, and local actors interact to produce emergent security governance.

The transformation of security from a public good provided by the state to a commodity exchanged on markets. Leander (2005) and Krahmann (2008) argue this undermines democratic accountability and creates profit-over-public-interest incentives.

A quantitative measure of how selectively a solid-state reaction produces the desired target phase versus competing byproduct phases, derived from thermodynamic reaction energies across all possible competing reactions in a chemical network.

Degree of geographic and firm-level concentration in advanced semiconductor fabrication. TSMC produces 92% of chips below 7nm. Taiwan, South Korea, and Japan dominate global fab capacity, creating extreme single-point-of-failure risk.

Proportion of test-set observations whose predicted sentiment label matches the human-labelled ground truth.

Macro-averaged F1 score across the three sentiment classes, weighting each class equally regardless of base-rate prevalence.

Correlation-style classification metric incorporating all four cells of the confusion matrix; robust to class imbalance.

The process by which solid-state ceramic synthesis proceeds through a sequence of binary reactions at precursor particle interfaces, where the most thermodynamically favorable pairwise reaction occurs first and intermediate phases progressively react to form the target product.

The size of economic activity not captured in official national accounts, including unreported market production, informal labor, and illegal activities, expressed as a percentage of official GDP. Key indicator of tax evasion potential and enforcement challenge. Commonly estimated via MIMIC (multiple indicators, multiple causes) methodology.

Risk-adjusted return metric: (portfolio return minus risk-free rate) divided by portfolio standard deviation. Measures return earned per unit of total risk. Used to compare strategies, optimize portfolios, and evaluate fund performance.

The local cation ordering in disordered rocksalt (DRX) cathode materials that deviates from a perfectly random distribution. SRO affects Li percolation networks, voltage profiles, and cycling stability in DRX cathodes.

Behavioral increase in education or training enrollment in the origin country in response to a new migration opportunity to a destination that demands that skill. The mechanism behind 'narrow' brain gain.

Total hours of sleep per 24-hour period, measured via polysomnography (gold standard), actigraphy (wearables), or self-report (ATUS, NHANES). Recommended 7-9 hours for adults (AASM). US average: 6.8 hours on workdays. Population-level data available from ATUS (N>200K), NHANES sleep module, and Fitbit aggregate studies (N>6M nights).

Composite measure of sleep efficiency (% time in bed asleep), number of awakenings, time in deep/REM sleep, and sleep onset latency. Pittsburgh Sleep Quality Index (PSQI) is the standard self-report instrument (0-21 scale, >5 = poor quality). Wearable devices now provide objective proxies at population scale.

The historical average excess return of small-capitalization stocks over large-capitalization stocks; the SMB factor in Fama-French models.

Community networks, norms, and trust that facilitate cooperation and collective action, enabling individuals and groups to achieve shared objectives.

Use of digital platforms by coup plotters or defenders during coup attempts. Social media can both enable coup coordination (solving the information problem described by Singh 2014) and enable resistance (organizing counter-mobilization). The Myanmar 2021 coup saw extensive social media use by both sides. Represents a technological update to Singh's focal point theory.

Geographic spread of supply chain disruptions where problems in one location increase the probability of disruptions in nearby locations through shared infrastructure, common suppliers, or correlated hazards.

The degree to which cations in a spinel structure (AB2X4) occupy non-ideal crystallographic sites (tetrahedral vs octahedral), often expressed as inversion fraction. Affects Mg migration pathways and electrochemical properties.

Government institutional strength and ability to provide security through national armed forces. Weak states are primary demand generators for PMSC services. Operationalized via GDP per capita, Polity scores, or composite fragility indices.

A composite measure of state weakness capturing effectiveness and legitimacy across security, political, economic, and social dimensions.

The Weberian principle that states hold exclusive legitimate authority over the use of force within their territory. McFate (2014) argues this was a brief historical interlude (1648-1990s), not the natural state of international politics. PMSC proliferation challenges this principle.

The headline legal rate applied to corporate profits before deductions, credits, and special provisions. The primary indicator of a country's CIT burden for location decisions by multinationals, though effective rates often diverge substantially.

The electrochemical voltage of sulfide-based cathode materials for Li-ion or multivalent batteries. Sulfide cathodes generally operate at lower voltages than oxides but may offer advantages in ionic conductivity and interface compatibility.

Number and distribution of alternative suppliers available for critical inputs, measuring redundancy in the supply base as a buffer against single-source failures.

Composite indicator of a supplier's financial stability and creditworthiness, predicting likelihood of operational failure or inability to fulfill orders.

Ease with which an alternative supplier can replace a disrupted one for a given input, considering technical specifications, qualification time, capacity, and cost. Low substitutability indicates lock-in and high disruption impact.

Binary indicator of whether a supply chain disruption event occurred in a given period. Disruptions include supplier failures, logistics interruptions, demand shocks, natural disasters, geopolitical events, and cyber attacks.

Composite measure of a supply chain's capacity to anticipate, prepare for, respond to, and recover from disruptions while maintaining continuous operations.

Degree to which a focal firm has access to timely and accurate information about supply chain partners' operations, inventories, and risk exposures across multiple tiers.

Multi-criteria composite measuring overall supply chain exposure to disruption, integrating geographic concentration, supplier financial health, network structure, demand volatility, and external threat environment.

Binary indicator equal to 1 if the government received external state support during the conflict-year, 0 otherwise. Government-side external support may strengthen counterinsurgency capacity and hasten war termination; included as a control in AR2013.

Binary indicator equal to 1 if rebels received external state support during the conflict-year, 0 otherwise. External support can prolong conflicts by replenishing rebel resources; AR2013 includes this as a control in the duration model.

Price levels where buying or selling pressure historically concentrated, causing price to pause or reverse. Derived from prior highs/lows, moving averages, volume nodes, and round numbers. Breakouts above resistance signal potential trend continuation.

ML-based prediction of optimal solid-state synthesis conditions (temperature, time, atmosphere) from precursor properties and reaction features, trained on text-mined literature data.

The degree to which machine learning synthesizability scores align with ground-truth thermodynamic metrics (convex hull energies, selectivity scores), measuring whether ML models correctly estimate the likelihood that a hypothetical material can be experimentally synthesized.

Quantitative measures (primary and secondary competition) of the thermodynamic favorability of target phase formation vs impurity phase formation in solid-state reactions. Higher selectivity indicates reactions that preferentially produce the desired product.

The fraction of computationally predicted target materials that are successfully synthesized in the laboratory. In the A-Lab autonomous synthesis platform, measured as the number of targets where XRD confirms the desired phase divided by the total number of attempted syntheses. Key metric for evaluating the practical utility of computational materials discovery.

The temperature (°C or K) at which a solid-state synthesis reaction is conducted. Must be high enough for sufficient kinetics but low enough to avoid unwanted side reactions or decomposition. Typical range for ceramics: 600-1400°C. ML models increasingly predict optimal synthesis temperatures.

ML prediction of optimal heating temperature for solid-state synthesis, learned from text-mined synthesis recipes. Correlated with precursor stability metrics (melting points, formation energies) following extended Tamman's rule.

Proportion of tax obligations that are voluntarily fulfilled by taxpayers, reflecting tax morale, administrative effectiveness, and perceived fairness of the tax system

The ratio of actual tax revenue to the predicted tax capacity given a country's structural characteristics (income, trade openness, sectoral composition, institutional quality). Values above 1 indicate above-capacity collection; below 1 indicates under-mobilization. Estimated via stochastic frontier analysis or OLS prediction.

The difference between taxes theoretically owed under full compliance and taxes actually collected, expressed as a percentage of theoretical liability or GDP. Decomposes into non-filing gap, underreporting gap, and underpayment gap. Estimated from random audit programs and administrative data matching.

The proportion of household financial wealth held in offshore tax havens, expressed as a share of total household financial assets. Estimated using discrepancies in international investment position data (Zucman 2013). Captures wealth concealment and tax avoidance by high-net-worth individuals.

The Kakwani index measures the progressivity of a tax system as the difference between the concentration coefficient of taxes paid and the Gini coefficient of pre-tax income. Positive values indicate a progressive tax (higher share paid by high earners); zero indicates proportional; negative indicates regressive.

Total tax revenue collected by government as a percentage of gross domestic product, measuring fiscal capacity and the overall tax burden on the economy

Structured synthesis datasets extracted from scientific literature using NLP/text mining methods. These datasets capture synthesis procedures, precursors, conditions (temperature, time, atmosphere), and outcomes for thousands of inorganic materials, enabling data-driven synthesis prediction.

A structured dataset of synthesis procedures extracted from scientific literature using NLP and text mining, containing precursors, conditions, and outcomes that enable data-driven analysis of synthesis-structure-property relationships.

The equilibrium yield of ammonia from solar thermochemical synthesis cycles involving metal nitride/oxide redox pairs, determined by Gibbs energy minimization across hydrolysis, reduction, nitrogen fixation, and nitride reformation steps.

The solar-to-fuel energy conversion efficiency (η) of a thermochemical water splitting cycle using metal oxide redox pairs. Depends on the reduction temperature, oxidation temperature, oxygen nonstoichiometry, and heat recovery. Typical values range from 5-40% depending on the oxide system and operating conditions.

The minimum energy difference (in meV/atom) between the most favorable initial reaction product and competing phases above which product formation is reliably predicted by thermodynamics alone, empirically determined to be approximately 60 meV/atom.

The ratio of thermodynamic driving force for the target synthesis product versus competing byproducts. Higher selectivity means the desired phase is strongly favored over alternative reaction products. Quantified as the free energy difference between the target reaction and the most favorable competing reaction pathway.

Binary classification of whether a crystal is thermodynamically stable (on the convex hull) or not. In Matbench Discovery, 15.3% of WBM test structures are stable. The primary classification target for discovery benchmarks.

Number of sequential supplier tiers between raw material extraction and final product delivery. Greater depth increases complexity, reduces visibility, and amplifies disruption propagation.

Maximum duration a downstream node can continue operations after an upstream disruption, given current inventory buffers and alternative sourcing capacity.

ML-derived or analytically derived tolerance factors (e.g., tau) that predict the stability and formability of perovskite-structured compounds based on ionic radii, oxidation states, and electronegativity.

The share of total national income accruing to the top decile, top 1%, or top 0.1% of earners; a key inequality measure responsive to top-marginal-rate policy.

The highest statutory marginal rate applied to personal income under the national income tax schedule, typically applying to the highest income bracket. Measures the maximum disincentive rate facing top earners and is central to debates about income redistribution and labor supply elasticity.

Descriptors derived from persistent homology (Betti curves) that compress electron density distributions into compact representations capturing bonding characteristics through components, cycles, and voids across electron density thresholds.

Betti curve descriptors derived from persistent homology that compress electron densities of crystalline materials into compact representations, capturing bonding characteristics by encoding topological features (components, cycles, voids).

A similarity metric between two crystalline materials based on the comparison of their persistent homology descriptors (persistence diagrams). Computed using Wasserstein or bottleneck distance between persistence diagrams derived from electron density fields. Enables structure-agnostic comparison of materials across different space groups.

Value or quantity of bilateral trade between countries or firms, serving as the primary measure of supply chain connectivity and economic interdependence.

Uncertainty about future trade policy (tariffs, quotas, sanctions, export controls) that increases supply chain planning difficulty and risk. Measured through text-based indices from news coverage of trade policy.

Responsiveness of origin-country training infrastructure (universities, vocational programs) to changes in demand for a skill induced by destination-country migration opportunities. A key moderator determining whether brain gain occurs.

Standard U.S. headline unemployment rate (BLS U-3) over the Beige Book sample period, used as a macroeconomic outcome variable.

The maximum expected loss over a given time horizon at a specified confidence level. CVaR measures the expected loss beyond the VaR threshold. Standard risk management metric for position sizing and portfolio risk.

The tendency for stocks with low price relative to fundamentals (low P/B, low P/E) to earn higher long-run returns than growth stocks. A core component of the Fama-French factor model. Debate continues about risk compensation vs. behavioral mispricing.

An approximate inference approach that recasts posterior inference as optimization: a tractable family of distributions is fit to the true posterior by minimizing KL divergence (equivalently, maximizing the ELBO). Trades exactness for scalability; the dominant approach for very large datasets and high-dimensional latent-variable models where MCMC is prohibitive.

The standard rate of value-added tax or goods-and-services tax applied to most consumption goods and services. Measures the broad consumption tax burden. Excludes reduced rates, zero-rating, and exemptions that apply to specific goods.

Price envelopes that expand and contract with volatility. Bollinger Bands (price plus/minus 2 standard deviations of MA) identify overextension and squeeze setups. Average True Range (ATR) measures volatility for position sizing and stop placement.

The principle that price moves are more reliable when accompanied by above-average volume. On-Balance Volume (OBV) accumulates volume on up-days, subtracts on down-days — divergence between OBV and price signals potential reversal.

The proportion of total tax obligations that are met by taxpayers without enforcement action — including on-time filing, accurate reporting, and timely payment. Complementary to the tax gap: VCR = 1 - (tax gap / theoretical liability). High voluntary compliance indicates strong tax morale and administrative effectiveness.

An emergent PMC archetype combining state-linked corrupt informal networks, paramilitary capabilities, and resource-extraction interests, exemplified by Russia's Wagner Group; does not fit traditional PMC typologies.

A prior designed to rule out implausible parameter values without strongly favoring any specific value — typically a wide but proper distribution (e.g. Normal(0, 2.5) on standardized coefficients, half-Cauchy on variance). Provides regularization and numerical stability without imposing strong subjective beliefs. Recommended default for applied Bayesian workflow.

Share of total national wealth held by the wealthiest 1 percent of the adult population

Probability of occupational injury or error per shift as a function of prior sleep. Workers sleeping <6 hours have 1.7x the accident risk of those sleeping 7-8 hours. After DST spring-forward (population loses 1 hour), US workplace injuries increase 5.7% and severity increases 67.6% on the following Monday.

The accuracy of automated X-ray diffraction pattern matching for identifying crystalline phases in synthesized materials. In autonomous synthesis workflows, this is the classification accuracy of ML models that interpret XRD patterns to determine whether the target phase was successfully produced.