search for: 1pl

I have just submitted irtoys_0.1.0, a package potentially useful for those working with IRT models. It can fit the 1PL, 2PL, and 3PL models through a simple and unified syntax, using either the R package ltm, Brad Hanson's ICL program, or the commercially available BILOG-MG. The purpose is basically to facilitate teaching, and especially comparisons across models and/or programs. Various graphs, item fit st...

...Partial Credit Model. The 'constraint' argument of gpcm() can be used to specify constrained versions of the model. Options are: - 'constraint = "rasch"' that fits the partial credit model (i.e., discrimination parameter fixed at one) - 'constraint = "1PL"' that specifies a single discrimination parameter, equal among items, and - 'constraint = "gpcm"' that specifies a different discrimination parameter per item. * gpcm() also allows for mixed type items, i.e., dichotomous and polytomous; however, for data sets...

Hello -- I am curious if lmer can be used to fit a multilevel factor model such as a two-parameter item response model. The one parameter model is straightforward. A two-factor model requires a set of factor loadings multiplying a single random effect. For example, a logit model for the ith subject responding correctly to the jth item (j=1,..,J) is logit[p(ij)] = a1*item1(i) + ... + aJ *

I have just submitted irtoys_0.1.0, a package potentially useful for those working with IRT models. It can fit the 1PL, 2PL, and 3PL models through a simple and unified syntax, using either the R package ltm, Brad Hanson's ICL program, or the commercially available BILOG-MG. The purpose is basically to facilitate teaching, and especially comparisons across models and/or programs. Various graphs, item fit st...

...Partial Credit Model. The 'constraint' argument of gpcm() can be used to specify constrained versions of the model. Options are: - 'constraint = "rasch"' that fits the partial credit model (i.e., discrimination parameter fixed at one) - 'constraint = "1PL"' that specifies a single discrimination parameter, equal among items, and - 'constraint = "gpcm"' that specifies a different discrimination parameter per item. * gpcm() also allows for mixed type items, i.e., dichotomous and polytomous; however, for data sets...

...first version of the package plink has been uploaded to CRAN. plink is a package for conducting unidimensional IRT scaling and chain linking for multiple groups for single-format or mixed-format common items. The package supports eight IRT models and four calibration methods. Dichotomous Models: 1PL, 2PL, 3PL Polytomous Models: -Graded response model -Partial credit model -Generalized partial credit model -Nominal response model -Multiple-choice model Calibration Methods: -Mean/Mean -Mean/Sigma -Haebara -Stocking-Lord Any combination of dichotomous and polytomous items can be supplied with...

...first version of the package plink has been uploaded to CRAN. plink is a package for conducting unidimensional IRT scaling and chain linking for multiple groups for single-format or mixed-format common items. The package supports eight IRT models and four calibration methods. Dichotomous Models: 1PL, 2PL, 3PL Polytomous Models: -Graded response model -Partial credit model -Generalized partial credit model -Nominal response model -Multiple-choice model Calibration Methods: -Mean/Mean -Mean/Sigma -Haebara -Stocking-Lord Any combination of dichotomous and polytomous items can be supplied with...

...methods. plink is a package for conducting unidimensional and multidimensional IRT-based test linking using separate calibration methods for multiple groups for single-format or mixed-format common items. The package supports sixteen IRT models and eleven calibration methods. Dichotomous Models: 1PL, 2PL, 3PL, M1PL, M2PL, M3PL Polytomous Models: -Graded response model, MD graded response model -Partial credit model, MD partial credit model -Generalized partial credit model, MD generalized partial credit model -Nominal response model, MD nominal response model -Multiple-choice model, MD multip...

...methods. plink is a package for conducting unidimensional and multidimensional IRT-based test linking using separate calibration methods for multiple groups for single-format or mixed-format common items. The package supports sixteen IRT models and eleven calibration methods. Dichotomous Models: 1PL, 2PL, 3PL, M1PL, M2PL, M3PL Polytomous Models: -Graded response model, MD graded response model -Partial credit model, MD partial credit model -Generalized partial credit model, MD generalized partial credit model -Nominal response model, MD nominal response model -Multiple-choice model, MD multip...