Statistics — Page 29
Explore statistical methods, their assumptions, interpretation and limitations.
Research field
Method family
Intention-to-Migrate Prediction
Intention-to-migrate prediction models stated plans to migrate as a forecast of actual migration behavior, taking seriously that what people say they will do is informative but imperfect. Migration surveys routinely ask whether respondents...
Interaction Equivalency
Interaction Equivalency is an evaluation method for validating that alternative input and output modalities (voice, gesture, eye tracking, switch control) provide functionally equivalent access to system capabilities compared to standard in...
Interactive Fixed Effects
Interactive Fixed Effects (IFE) extends standard fixed-effects panel models by allowing unit-specific intercepts to vary not just at the individual level but also with unobserved common time-varying factors. Introduced by Bai (2009), it mod...
Interest Rate Models
Interest rate models are structural models that describe how interest rates evolve over time within a stochastic differential equation framework. The family covers Vasicek's normal short-rate process (1977), the CIR square-root process, the...
Intergenerational Elasticity
The intergenerational elasticity of income (IGE) is the workhorse measure of economic mobility: the regression coefficient from regressing a child's adult log income on the parent's log income. It expresses the percentage by which a child's...
Interrater Reliability
Interrater reliability quantifies the degree to which two or more independent raters produce consistent scores when evaluating the same individuals or products. The family encompasses Cohen's kappa, introduced in 1960 for categorical judgme...
Interrupted Time Series
Interrupted Time Series analysis is a quasi-experimental design that estimates the effect of a single, well-dated intervention by comparing the trajectory of an outcome before and after it occurs. Formalised as segmented regression by Wagne...
Interrupted Time Series in Education Research
Interrupted time series (ITS) analysis is a quasi-experimental design that estimates the causal effect of an education policy or intervention by examining whether an outcome trend changes abruptly at the point of implementation. Applied to...
Intervening Opportunities Model
The intervening opportunities model, introduced by Samuel Stouffer in 1940, explains the volume of migration between two places not by the physical distance separating them but by the number of opportunities available at the destination rel...
Intraclass Correlation Coefficient
The Intraclass Correlation Coefficient (ICC) is a parametric reliability statistic that quantifies the degree of agreement or consistency among repeated measurements or multiple raters on a continuous outcome. The modern six-form taxonomy w...
Inverse Distance Weighting
Inverse distance weighting is a simple, deterministic method for estimating values at unsampled locations by taking a weighted average of nearby measured points, where closer points carry more weight. Introduced by Donald Shepard in 1968, i...
Inverse Probability Weighting
Inverse Probability Weighting is a causal-inference method that assigns each observation a weight equal to the inverse of its probability of receiving the treatment it actually received. Introduced by Robins, Hernán and Brumback (2000) for...
Inverse Probability Weighting in Education Research
Inverse Probability Weighting (IPW) is a causal inference technique that reweights observational education data to mimic a randomised experiment. Each student or school is assigned a weight equal to the inverse of the probability they recei...
Iowa Gambling Task
The Iowa Gambling Task (IGT) is a laboratory analog of real-world decision-making that measures how individuals make risky choices when outcomes are uncertain. Participants select cards from four decks, each offering different patterns of r...
Isomap
Isomap (Isometric Feature Mapping) is a manifold learning algorithm introduced by Tenenbaum, de Silva, and Langford in 2000 that discovers the intrinsic low-dimensional geometry of high-dimensional data by preserving geodesic — rather than...
Item Analysis
Item analysis is the foundational psychometric procedure for evaluating the quality of individual test or scale items within the Classical Test Theory (CTT) framework, as systematised by Allen and Yen (1979) and Crocker and Algina (1986). I...
Item Response Theory
Item response theory models the probability that a respondent answers an item correctly (or endorses it) as a function of the respondent's latent trait level and the item's own statistical properties — difficulty, discrimination, and guessi...
Jackknife
The jackknife is a classical resampling method that estimates the bias and variance of a statistic by systematically recomputing it with one observation left out at a time. Introduced by Quenouille in 1956 and later reviewed by Miller in 19...
Jackknife Estimation
Jackknife estimation is a classical resampling technique that computes the bias and variance of a statistical estimator by systematically leaving out one observation at a time and re-computing the statistic on each reduced sample. Introduce...
Job Characteristics Model
The Job Characteristics Model (JCM) is the foundational theory of work design in organizational behavior, developed by J. Richard Hackman and Greg Oldham in the mid-1970s. It proposes that five core job dimensions — skill variety, task iden...
Job Crafting Scale
The Job Crafting Scale measures the proactive, self-initiated changes employees make to their own jobs, a construct introduced by Amy Wrzesniewski and Jane Dutton in 2001. Where classic work-design theory treated jobs as fixed structures ha...
Job Demands-Resources Model
The Job Demands-Resources (JD-R) model is a flexible framework in organizational behavior and occupational health psychology that explains employee well-being and performance through two parallel processes. Introduced by Demerouti, Bakker,...
Johansen Cointegration Test
The Johansen procedure is a multivariate cointegration framework, introduced by Søren Johansen in 1991, that tests for long-run equilibrium relationships among several I(1) time series. It determines how many cointegrating vectors link the...
Joint Model for Longitudinal and Survival Data
The joint model for longitudinal and time-to-event data, formalised by Tsiatis and Davidian in 2004 and extended comprehensively by Rizopoulos in 2012, simultaneously estimates a mixed-effects model for repeatedly measured biomarkers and a...