Estimation of a four-parameter item response theory model

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Kelly L. Rulison, Associate Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: We explore the justification and formulation of a four-parameter item response theory model (4PM) and employ a Bayesian approach to recover successfully parameter estimates for items and respondents. For data generated using a 4PM item response model, overall fit is improved when using the 4PM rather than the 3PM or the 2PM. Furthermore, although estimated trait scores under the various models correlate almost perfectly, inferences at the high and low ends of the trait continuum are compromised, with poorer coverage of the confidence intervals when the wrong model is used. We also show in an empirical example that the 4PM can yield new insights into the properties of a widely used delinquency scale. We discuss the implications for building appropriate measurement models in education and psychology to model more accurately the underlying response process.

Additional Information

Publication
The British Journal of Mathematical and Statistical Psychology, 63(3), 509-525
Language: English
Date: 2010
Keywords
four-parameter item response theory model, delinquency scale, measurement models

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