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  • Polytomous item response theory parameter recovery: An investigation of non-normal distributions and small sample size
  • Bahry, Louise M
  • English
  • Item Response Theory
    Graded Response Model
    Parameter Recovery
  • Jan 31, 2012 12:12 PM
  • Thesis
  • English
  • Adobe PDF
  • 1103189 bytes
  • Item Response Theory (IRT) has been extensively used in educational research with large sample sizes and normally distributed traits. However, there are cases in which distributions are not normal, and research has shown that the estimation of parameters becomes problematic with non-normal data. This study investigates the effects of skewness on parameter estimation using the Graded Response Model (GRM) and MULTILOG. Three distribution types (extreme and moderate skewness and a baseline condition (i.e. normal) and seven sample sizes (from n = 100 to n = 3,000) were investigated using simulations. In keeping with previous findings, the extremely skewed distribution condition resulted in the poorest estimates regardless of sample size. In general, the accuracy of parameter estimation increased as sample size increased. For the normally distributed conditions, results suggest a minimum sample size of 750 for accurate estimation. Implications of these findings are discussed.
  • Master's
  • Master of Education
  • Department of Educational Psychology
  • Measurement, Evaluation and Cognition
  • Spring 2012
  • Rogers, W. Todd (Educational Psychology)
  • Cui, Ying (Educational Psychology)
    Varnhagan, Connie (Psychology)

Apr 28, 2014 3:24 PM


Jan 31, 2012 12:12 PM


Kim Punko