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Comment
. 2016 Dec;81(4):1093-1097.
doi: 10.1007/s11336-016-9519-8. Epub 2016 Sep 19.

A Note on the Identifiability of Fixed-Effect 3PL Models

Hao Wu  1
Affiliations
Comment

A Note on the Identifiability of Fixed-Effect 3PL Models

Hao Wu. Psychometrika. 2016 Dec.

Abstract

In this note, we prove that the 3 parameter logistic model with fixed-effect abilities is identified only up to a linear transformation of the ability scale under mild regularity conditions, contrary to the claims in Theorem 2 of San Martín et al. (Psychometrika, 80(2):450-467, 2015a).

Keywords: 3PL model; identification; item response theory.

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References

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