GGUM2004 is a Windows-based program that estimates parameters in the generalized graded unfolding model (GGUM; Roberts, Donoghue, & Laughlin, 2000). It expands the capabilities of its predecessor, GGUM2000, in the following ways:
GGUM2004 provides a user-friendly Windows interface that enables the user to prepare command files, run the core estimation program, and display results.
GGUM2004 allows different questionnaire items to have varying numbers of response categories. This is especially useful when sparse responses make recoding into a fewer number of response categories necessary.
GGUM2004 allows for item responses that are missing at random.
GGUM2004 incorporates new item fit statistics with desriable statistical qualities.
GGUM2004 provides a series of diagnostic graphics that enable to user to deduce how well the model is performing.
GGUM2004 enables users to perform DIF analysis using unfolding IRT models.
GGUM2004 is available free of charge and can be downloaded using the link below. Users are encouraged to join the GGUM2004 Message Group to obtain the latest information about the program.
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