Statistics — Page 9
Explore statistical methods, their assumptions, interpretation and limitations.
Research field
Method family
Short form nomological validity
Short form nomological validity examines whether an abbreviated version of a psychological scale preserves the pattern of theoretically expected correlations with conceptually related and unrelated constructs. It is a cornerstone step in ju...
Short-Form CFA
Short-form confirmatory factor analysis applies CFA to a reduced subset of items drawn from a longer validated scale, testing whether the abbreviated version preserves the original factor structure with acceptable model fit and reliability....
Short-Form IRT
Short-form item response theory applies IRT calibration and scoring to abbreviated or shortened psychological scales. It uses item information functions to guide which items to retain from a full-length instrument, then estimates latent tra...
Short-Form Scale Development
Short-form scale development is the systematic process of reducing a full-length psychological scale to a smaller subset of items while preserving the construct validity, reliability, and measurement properties of the original instrument. I...
Short-form Cronbach's alpha
Short-form Cronbach's alpha quantifies the internal consistency reliability of an abbreviated version of a psychological scale. It applies Cronbach's alpha formula to a reduced item set, verifying that the shortened instrument retains suffi...
Short-form McDonald's omega
Short-form McDonald's omega applies the omega reliability coefficient to abbreviated or shortened versions of psychological scales. It provides a theoretically sound reliability estimate that accounts for the multidimensional structure of t...
Short-form item analysis
Short-form item analysis is the systematic psychometric evaluation and selection of items when constructing an abbreviated version of a longer measurement instrument. It applies classical and modern item-analysis criteria — item-total corre...
Short-form reliability analysis
Short-form reliability analysis evaluates whether an abbreviated version of a psychological scale maintains acceptable internal consistency, validity, and structural integrity after items are removed. It is used in survey and assessment res...
Short-form test-retest reliability
Short-form test-retest reliability quantifies how consistently an abbreviated version of a measurement instrument produces the same scores across two administrations separated by a defined time interval. It is a critical validation step whe...
Signal Detection Theory
Signal Detection Theory (SDT) is a framework for analyzing how observers detect signals embedded in noise, accounting for both sensory capacity and decision-making bias. Developed by Green and Swets in the 1960s, it provides a principled me...
Social Relations Model
The Social Relations Model (SRM), developed by David Kenny and colleagues, is a variance-decomposition framework for analyzing interpersonal perception and behavior in groups. When every member of a group rates (or behaves toward) every oth...
Stop-Signal Reaction Time
The Stop-Signal Reaction Time (SSRT) task is a behavioral measure of response inhibition and executive control. Participants make rapid responses to go signals but must cancel responses when an occasional stop signal appears. By analyzing h...
Stroop Task
The Stroop task is a classic measure of cognitive control and selective attention. Participants name the color of words while ignoring the words' semantic content. When the color and word meaning match (e.g., the word 'red' printed in red i...
Support for Political Violence Measure
This measure assesses citizens' willingness to endorse violence against political opponents, a key indicator of democratic fragility. Nathan Kalmoe and Lilliana Mason's research, synthesized in Radical American Partisanship (2022), maps a c...
Test Equating
Test equating is a family of statistical methods that converts scores earned on one test form onto the score scale of another form, so that scores from different administrations or versions can be compared and reported on a common metric. T...
Test-Retest Reliability
Test-retest reliability quantifies the temporal consistency of a measure by correlating scores obtained from the same participants on two separate occasions. It is a cornerstone of psychometric validation, directly indicating whether a scal...
Ultimatum Game
The Ultimatum Game is a two-player economic decision-making task that reveals preferences for fairness and social norms. One player (proposer) receives money and offers a portion to a second player (responder). The responder accepts or reje...
Value-Added Modeling
Value-Added Modeling (VAM) is a method for assessing the contribution of schools or teachers to student achievement growth, developed by Sanders and Horn (1998). VAM isolates the effect of a teacher or school by comparing student gains (val...
Wordfish
Wordfish is a statistical model for scaling documents on latent dimensions, developed by Slapin and Proksch (2008). Unlike reference-based methods like Wordscores, Wordfish uses a Poisson generative model to jointly estimate word frequencie...
Wordscores
Wordscores is a text-based scaling method developed by Laver, Benoit, and Garry (2003) that estimates the policy positions of political actors based on word frequencies in their texts. By comparing word usage in reference texts of known pos...