ResidPlots 2.0

ResidPlots-2, is to provide a powerful tool for graphical residual analyses. ResidPlots-2 supports the most widely used IRT models including three dichotomous models (1PLM, 2PLM, 3PLM) and three polytomous models (GRM, GPCM, NRM).
ResidPlots-2 provides considerable flexibility with respect to the number and size of the intervals for which the residuals are computed. Different data have different features and therefore it is beneficial to give users choices about the intervals.
For example, users are able to decide number of intervals, choose the interval size to provide equal width or equal frequency, select the location of the data plot in each interval, eliminate intervals at the lower or higher end of the proficiency scale if desired.
ResidPlots-2 provides three sets of plots, first, at the item level, raw residual plots and standardized residual plots with error bars, second, at the test level, ResidPlots-2 can show standardized residual distributions (PDF and CDF) with corresponding tables, item fit plots and score fit plots from both empirical and simulated data, and finally, observed test score distributions and predictive score distributions (PDF and CDF) are produced too.
The predictive test score distribution is based on simulation data generated from item and ability parameter estimates from the observed data.