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%                    ORDINAL DATA MODELING 
%                VALEN JOHNSON AND JAMES ALBERT
%                     CHAPTER 6 TOOLBOX
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%                  Jim Albert - October 1, 1998
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%                Basic fitting programs
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% item_r - Bayesian fit of two-parameter item response model - probit link
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% l_itemr - Bayesian fit of two-parameter item response model - logit link
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% item_r1 - Bayesian fit of one-parameter item response model - probit link
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% item_r_h - Bayesian fit of two-parameter item response model - probit link
%            exchangeable model placed on item slope parameters
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%                Additional programs
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% irtobs - computes observed proportion of correct for groups of latent ability
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% ir_curve - computes values of the probability of correct response (probit link)
%            for selected values of item parameters -- useful for plotting item 
%            response curves
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% irtpost - computes 5th, 50th, 95th percentiles of posterior of item response
%           curve - probit link
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% plotpost - computes 5th, 50th, 95th percentiles and graph of each component of
%           a matrix of simulated values
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%               Datasets and sample runs
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% ratings.dat - shyness rating dataset from Chapter 6
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% place98.dat - math placement dataset in exercises of Chapter 6
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% example.m - m-file illustrating computations for ratings dataset
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