libirt A library to help you with your work.
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item Estimate estimation questionnaire estimate item estimate ability questionnaire subject

libirt Description

libirt is a set of useful functions intended to help you estimate the items and abilities from the responses of subjects to specific questionnaires. MODELS: · 1PLM - One parameter logistic model. The threshold (difficulty or location parameter) of each item is estimated while the slope (discrimination or scale parameter) of each item can be fixed. · 2PLM - Two parameters logistic model. Both the threshold and slope of each item are estimated. · 3PLM - Three parameters logistic model. The threshold, slope and asymptote (guessing parameter) are estimated. · Bock's nominal response model - The threshold and slope of each option are estimated. · Samejima's graded response model - The modal threshold of each option and the slope of each item are estimated. · Nonparametric - In addition to the parametric models, libirt can estimate the response functions by smoothing

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