ERIC Number: EJ1027887
Record Type: Journal
Publication Date: 2013
Abstractor: As Provided
Reference Count: N/A
Local Equating Using the Rasch Model, the OPLM, and the 2PL IRT Model--or--What Is It Anyway if the Model Captures Everything There Is to Know about the Test Takers?
von Davier, Matthias; González B., Jorge; von Davier, Alina A.
Journal of Educational Measurement, v50 n3 p295-303 Fall 2013
Local equating (LE) is based on Lord's criterion of equity. It defines a family of true transformations that aim at the ideal of equitable equating. van der Linden (this issue) offers a detailed discussion of common issues in observed-score equating relative to this local approach. By assuming an underlying item response theory model, one of the main features of LE is that it adjusts the equated raw scores using conditional distributions of raw scores given an estimate of the ability of interest. In this article, we argue that this feature disappears when using a Rasch model for the estimation of the true transformation, while the one-parameter logistic model and the two-parameter logistic model do provide a local adjustment of the equated score.
Descriptors: Equated Scores, Transformations (Mathematics), Item Response Theory, Raw Scores, Statistical Distributions, Computation, Models
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Publication Type: Journal Articles; Reports - Evaluative
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