Erratum to: On the Unidentifiability of the Fixed-Effects 3PL Model

Erratum to: PSYCHOMETRIKA, 2015, 80, 450–467 DOI 10.1007/s11336-014-9404-2

Condition 2 of Theorem 2 was incorrect in the published version. The correct condition 2 appears in this erratum.

FormalPara Theorem 2

Suppose that $I\ge 3$ for the fixed-effects 3PL model. If $\omega _1=(\alpha _1,\beta _1,c_1)$ is fixed at (1, 0, 0), then

• 1. The person parameters are identified by the observations.

• 2. The item parameters $(\varvec{\alpha }_{2:J}, \varvec{\beta }_{2:J},\varvec{c}_{2:J})$ are not identified by the observations.