Method evidence record

2PL IRT

The two-parameter logistic item response model, formalised by Frederic Lord (1980), describes the probability that a respondent answers a binary test item correctly as a smooth S-shaped function of the respondent's latent ability. By estimating a separate discrimination parameter for each item alongside a difficulty parameter, 2PL allows items to differ in how sharply they distinguish high- from low-ability respondents — making it the standard model for large-scale educational and psychological assessments.

Sources recorded, not reviewed

Source record

Citations copied verbatim from the method’s source record. No claim-level verification is inferred from them.

Two-Parameter Logistic Item Response Model

Taxonomic method record · latent-structure / psychometrics

Lord, F. M. (1980). Applications of Item Response Theory to Practical Testing Problems. Erlbaum. · URL
Embretson, S. E. & Reise, S. P. (2000). Item Response Theory for Psychologists. Erlbaum. · ISBN 978-0805828191

Open full method

Curated claims

Claims persisted in the evidence ledger, each with its own assessment.

No curated claims yet

This view does not invent a claim assessment when the ledger has none.

Related methods

Generated from the method graph and shown as machine-suggested relations — no evidence claim is inferred.

Same method family3PL IRTmachine-suggested · Relational suggestion, not evidence.Same method familyConfirmatory factor analysismachine-suggested · Relational suggestion, not evidence.Same method familyCronbach's Alphamachine-suggested · Relational suggestion, not evidence.Same method familyEFAmachine-suggested · Relational suggestion, not evidence.Same method familyGRMmachine-suggested · Relational suggestion, not evidence.Same method familyRasch Modelmachine-suggested · Relational suggestion, not evidence.