Psychometrika

, Volume 16, Issue 3, pp 285–296 | Cite as

Effect of group heterogeneity on item parameters

  • Harold Gulliksen
Article
Received:

Abstract

Most indexes of item validity and difficulty vary systematically with changes in the mean and variance of the group. Formulas are presented showing how certain item parameters will vary with these alterations in group mean and variance. Item parameters are also suggested which should remain invariant under such changes. These parameters are developed under two different assumptions: first, the assumption that thetotal distribution of the item ability variable is normal, and, second, that the distribution of the item ability variablefor each array of the explicit selection variable is normal.

Keywords

Public Policy Statistical Theory Selection Variable Group Heterogeneity Item Parameter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Psychometric Society 1951

Authors and Affiliations

  • Harold Gulliksen
    • 1
  1. 1.Educational Testing ServiceUSA

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