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.
Theorem 2
Suppose that \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$I\ge 3$$\end{document}
for the fixed-effects 3PL model. If \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\omega _1=(\alpha _1,\beta _1,c_1)$$\end{document}
is fixed at (1, 0, 0), then
-
1. The person parameters are identified by the observations.
-
2. The item parameters \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\varvec{\alpha }_{2:J}, \varvec{\beta }_{2:J},\varvec{c}_{2:J})$$\end{document}
are not identified by the observations.
