The IRT Procedure
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Overview
- Getting Started
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Syntax
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DetailsNotation for the Item Response Theory ModelAssumptionsPROC IRT Contrasted with Other SAS ProceduresResponse ModelsMarginal LikelihoodApproximating the Marginal LikelihoodMaximizing the Marginal LikelihoodFactor Score EstimationModel and Item FitItem and Test informationMissing ValuesOutput Data SetsODS Table NamesODS Graphics
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Examples
- References
MODEL Statement
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MODEL model-specification <, model-specification …>;
where model-specification is defined as variable-list < / model-option > The MODEL statement specifies the items and their response functions or models. You can specify different response models for different items. In the variable-list, you specify the set of variables that use the same model.
You can specify the following model-option:
You can specify mixed response models for different items as follows:
proc irt; model x1-x10/resfunc=twop, x11-x20/resfunc=graded, x21-x30/resfunc=threep; run;
For variables that are also listed in the VAR statement, the model that is specified here overwrites the default model or the model that is specified by using the RESFUNC= option in the PROC IRT statement.
You can use the EQUALITY statement to set equality constraints on these parameters.