Presentations

• Introduction to the Item Response Theory Tutorial Symposium.

• Selecting IRT Models for Cognitive and Noncognitive Data.

• Examining Model-Data Fit Using Graphical and Statistical Methods.

• Using IRT Methods for Test Construction: Creating Parallel Forms.

• Methods for Detecting Differential Item/Test.

Programs

• Please extract zip files in your target folder (any folder you create).

• MODFIT plots theoretical item response functions and examine the fit of dichotomous or polytomous IRT models to response data. You may review MODFIT instructions here.

• ITERLINK performs iterative linking and pairwise DIF detection for the 3PL IRT model using Lord's chi-square. You may review ITERLINK instructions here.

• PARTO3PL (Win9x series), PAR_3PL (WinNT & Win2k series) will convert original BILOG for DOS/Windows generated parameter file (*.PAR) in that folder, delete the first four lines (title/comment information) and subsequent alternating rows (standard errors), and rename the files using the *.3PL extension by following the 32x,2f12.6,12x,f12.6 format (which can be used for running ITERLINK). PAR_3PL will also retain 3 columns of a, b, c parameters only in a 3PL model (from columns 4, 5, and 7 of the original BILOG's *.PAR file, and rename the file using the *.TXT extension (free-field format), which is compatible with ParConversion.

• PAR3PLMG will convert original BILOG-MG generated parameter file (*.PAR) in that folder, delete the first four lines (title/comment information), remove standard error columns, and rename the files using the *.3PL extension by following the 32x,2f12.6,12x,f12.6 format, which can be used for running ITERLINK). PAR3PLMG will also retain 3 columns of a, b, c parameters only in a 3PL model (from columns 4, 6, and 10 of the original BILOG-MG's *.PAR file), and rename the file using the *.TXT extension (free-field format), which is compatible with ParConversion.

• COVMG will convert original BILOG-MG generated covariance file (*.COV) in that folder, and rename the file using the *.CVM extension (old BILOG format) for further analysis (e.g., ITERLINK)

• ParConversion (requires Microsoft .NET Framework through Windows update) will convert original BILOG for DOS/Windows generated parameter files (*.PAR) in that folder, delete the first four lines (title/comment information) and subsequent alternating rows (standard errors), retain 3 columns of parameters a, b, c only in a 3PL model (from columns 4, 5, and 7 of original BILOG's *.PAR file), and rename the files using *.TXT extension (free-field format).

• DFITD4 identifies DIF items, computes DTF, and when DTF is found, determines which DIF items, if any, should be removed to establish measurement equivalence. You may review DFITD4 instructions here.

Datasets and syntax

BILOG-MG sample syntax and output files are available for download here

Excel files

• Parallel Forms 3PL.xls creates parallel forms using IRT. You may review Parallel Forms 3PL.xls instructions here.
  
  
• Parallel Forms_25 items 3PL.xls creates parallel forms using IRT. You may review Parallel Forms 3PL.xls instructions here.
  
  
• Parallel Forms_20 SGR items.xls creates parallel forms using the SGR model (5 options). You may review Parallel Forms 20 SGR items.xls instructions here.

Other IRT programs

• BILOG estimates IRT Parameters for the 1-, 2-, or 3-parameter logistic model using marginal maximum-likelihood.

• BILOG-MG estimates IRT parameters for multiple groups, allowing detection of differential item functioning.

• MULTILOG performs multiple-category IRT analysis for polytomous IRT models.

• PARSCALE performs IRT Scaling, Item Analysis, and Scoring or Rating Scale Data.

• XCALIBRE performs Marginal maximum-likelihood IRT parameter estimation with small numbers of examinees or short tests, for the 2- and 3-parameter IRT model.

• DETECT examines the signs and magnitudes of estimated conditional item pair covariances, given observed score on the remaining items.

• DIMTEST assesses lack of unidimensionality, operating in either a confirmatory mode.

• SIBTEST assesses single items for DIF or bundles of items for simultaneous DIF.