Assumptions
This chapter offers an in-depth discussion of the three statistical assumptions of item response theory (IRT), namely unidimensionality, local independence, and correct model specification. Each of these assumptions is described more fully, with a focus on procedures for testing each assumption. For each assumption, a number of statistical tests is proposed and explored in the literature. In addition, three common methods for testing unidimensionality are discussed: analysis of the eigenvalues of the inter-item correlation matrix, Stout's test of essential unidimensionality, and indices based on the residuals from a unidimensional solution. Weaknesses of some common approaches and indices is noted, and newer alternative procedures are described. Unfortunately, some of these procedures are quite complex and not easily implemented.
Keywords: statistical assumptions, item response theory, unidimensionality, local independence, correct model specification
Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.
Please, subscribe or login to access full text content.
If you think you should have access to this title, please contact your librarian.
To troubleshoot, please check our FAQs , and if you can't find the answer there, please contact us .