IRT Separate Calibration Linking Methods

Item response theory based methods are used to compute linking constants and conduct chain linking of unidimensional or multidimensional tests for multiple groups under a common item design. The unidimensional methods include the Mean/Mean, Mean/Sigma, Haebara, and Stocking-Lord methods for dichotomous (1PL, 2PL and 3PL) and/or polytomous (graded response, partial credit/generalized partial credit, nominal, and multiple-choice model) items. The multidimensional methods include the least squares method and extensions of the Haebara and Stocking-Lord method using single or multiple dilation parameters for multidimensional extensions of all the unidimensional dichotomous and polytomous item response models. The package also includes functions for importing item and/or ability parameters from common IRT software, conducting IRT true score and observed score equating, and plotting item response curves/surfaces, vector plots, information plots, and comparison plots for examining parameter drift.


News

Changes in version: plink_1.5-1

Bug Fixes: o The manner in which the plot history was being saved created issues when installing the package on non-Windows machines. This functionality has been temporarily disabled

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Changes in version: plink_1.5-0

o The vignette was cleaned up and the package was re-added to CRAN

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Changes in version: plink_1.4-0

Bug Fixes: o A correction was made to the sep.pars function. An incorrect sign was used to tranform item parameters with a location parameter to parameters without a location parameter, and vice versa.

o A correction was made to the linking function when there is only one common dimension between multidimensional tests (or when linking a unidimensional and multidimensional test

o The function {read.ltm} was not importing all of the threshold parameters for the graded response model.

Added Functionality:

o The functions {drm}, {grm}, {gpcm}, {nrm}, and {mixed} can now be used to compute unidimensional and multidimensional item information

o An argument {exclude} was added to the equate function to allow items to be removed before computing total scores

Misc:

o The composite angle is now printed when vectorplot2 is used

o Output for observed score equating now includes EAP equivalents (and standard deviations) for each of the observed scores

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.3-1

Bug Fixes:

o The value for D in {mixed} defaulted to 1 even when the argument was changed

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Changes in version: plink_1.3-0

Bug Fixes:

o The scoring function for {equate} accidentally defaulted to 2 instead of 1.

o True score equating using the graded response model returned an error.

Added Functionality:

o Least squares estimation added for the ODL, MIN, and LL methods for multidimensional linking. This can be specified by setting the argument {method="LS"}. When dilation="ODL" this uses the oblique procrustes rotation and returns the same results previously returned by method="RM". In previous versions, the MIN and LL methods could only be used with the characteristic curve methods. The "LS" method is the now the default estimation approach for multidimensional linking given that the results are more stable than with the characteristic curve methods.

o Argument {items} added to drm, grm, gpcm, nrm, mcm, and mixed that allows probabilities to be computed for a subset of items

Misc:

o The default dilation for multidimensional linking was changed from "MIN" to "LL". This is because the LL method is technically the only method that produces a symmetric transformation.

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.2-7

Bug Fixes:

o The function read.multilog returned an error when the items are modeled using a combination of the 2PL and 3PL.

o The read.ltm function returned an error when trying to import mixed-format item parameters estimated using grm or gpcm

Misc:

o The sep.pars function was changed to allow individuals to specify grm and gpcm items with only two response categories.

o The group names for the object returned by drm, grm, gpcm, nrm, mcm, and mixed defaults to the group names for the irt.pars object

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Changes in version: plink_1.2-6

Bug Fixes:

o The function read.multilog did not import item parameters properly when certain polynomial contrasts were specified.

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Changes in version: plink_1.2-5

Bug Fixes:

o When no starting values were specified when linking Rasch items, the characteristic curve estimation would crash.

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Changes in version: plink_1.2-4

o A vignette was added which explains unidimensional linking with plink

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Changes in version: plink_1.2-3

Bug Fixes:

o Multidimensional item and ability parameters were not properly rescaled with more than two groups when not all dimensions are common

o The get.prob function was not automatically loaded with the package

Added Functionality:

o Function read.erm added to allow item parameters to be imported from the eRm package

o Argument {save.hist} added to the plot functions. In previous versions any plot history was eliminated prior to producing new plots. The new default is to not delete any plot history

Changed Functionality:

o The startvals argument for plink can now be specified as a list so that different starting values can be used for different pairs of tests

o The default argument for {dilation} in plink changed to "MIN"

Misc:

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.2-2

Bug Fixes:

o The creation of an irt.pars object for multiple groups when there are location parameters in one or more sets of items was returning an error

o The specification of explicit scoring weights in plink and equate when there are multiple groups could return an error

o No ability descriptives were printed when using the summary function when there are multiple groups

Added Functionality:

o Function get.prob added to extract expected probabilities from irt.prob objects

Misc:

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.2-1

Changed Arguments:

o The mn.exclude argument in the plink function has been replaced with a more general argument exclude that allows common items associated with any response model, or specific items, to be excluded when estimating the linking constants

Added Functionality:

o The plink function now allows NRM and MCM items to be used for the Stocking-Lord method (note: caution should be taken when using these models because TCCs are not adequately defined unless the parameters correspond to ordered categories)

o The MCM can now be used for true-score and observed score equating

Plotting:

o Item numbers can now be plotted on the drift plots for the parameter comparisons

o ICCs and TCCs can now be plotted as part of the drift argument

o An argument drift.sd has been added to change the size of the confidence region for the parameter comparison plots

o The comparison plots now use the SD line rather than the 45 degree line

Misc:

o Summary function now prints descriptive statistics for rescaled ability estimates when summarizing the output from plink (if applicable)

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.2-0

o Function equate added for conducting IRT true score and observed score equating

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.1-6

Bug Fixes:

o Upper and lower bounds for the estimates for the characteristic curve methods were removed because they have the potential to result in inaccurate estimates when there are three or more groups

o The specification of different weights for different pairs of groups now works properly

Misc:

o A warning message was added to the Reckase-Martineau approach when the rotation matrix is not positive definite

o Group name labels added to plots for multiple groups

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.1-5

Bug Fixes:

o IMPORTANT - in the plink function, the incorrect parameters were being optimized for the multidimensional characteristic curve methods

o Fix for the separation of multidimensional NRM and multidimensional MCM item parameters in the sep.pars function

Changed Arguments:

o The default value for the rescale.com argument in plink has been changed from FALSE to TRUE

o The weights argument in plink changed to weights.t and weights.f

o The functionality of the mn.exclude argument in plink was changed

Plotting:

o Included functionality to plot comparisons of common item parameters, for examining parameter drift

o Now able to plot results for multiple groups

o Plot function includes additional arguments - drift, groups, grp.names, and sep.mod (see the documentation for more info)

Misc:

o Updates to the class definition for irt.prob. This class now includes a slot for scaling constants D

o Additional validation checks (and error comments) have been added to the irt.pars class and sep.pars class

o All of the source code now includes extensive comments

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.1-4

Bug Fixes:

o Fix in plink for scenarios where there is only a single polytomous item corresponding for a given model

Changed Arguments:

o The default value for the as.irt.pars argument for the functions read.bilog, read.parscale, read.multilog, read.testfact, read.icl read.bmirt, and read.ltm was changed to TRUE

o The default value for D in the functions drm, gpcm, and grm was changed from D = 1.7 to D = 1. NOTE: This will change estimated linking constants relative to previous versions unless D is explicitly set to D = 1.7.

o New argument rescale.com was added to the plink function

o New argument sign.adjust was added to the read.bmirt function

Misc:

o Arguments D.drm, D.gpcm, and D.grm can be passed to plink, mixed, and plot to specify different scaling constants for the respective models

o Functionality was added to create panels of vectorplots when the items measure more than two dimensions

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.1-3

Bug Fixes:

o Fix for the plot function related to sending plots to an external file

Changed Arguments:

o The default value for the symmetric argument in the plink function was changed to FALSE

Misc:

o The plink function was modified to speed up convergence for the characteristic curve methods (particularly for the multidimensional methods)

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.1-2

Bug Fixes:

o Fix for the function read.bmirt when importing item parameters

o Fix in sep.pars for the re-ordering of items

o Fix for plot.irt.pars regarding how arguments are passed

o Fix for plot.irt.prob for the default axes ranges for the three vectorplots

Misc:

o Some corrections to the .Rd files

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Changes in version: plink_1.1-1

Bug Fixes:

o Miscellaneous fixes for the functions read.icl and read.bmirt

o Fix for the matrix formulation of theta for multidimensional models for drm, grm, gpcm, nrm, mcm, and mixed

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Changes in version: plink_1.1-0

o Functions read.multilog, read.icl, read.bmirt, and read.ltm added for importing item/ability parameters from MULTILOG, ICL, BMIRT, and ltm respectively

o Some corrections/additions to the .Rd files

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Changes in version: plink_1.0-0

This is a major version change. All of the unidimensional item response models and linking methods have been extended to the multidimensional case. Arguments have been added to various functions that are relevant for the multidimensional extensions.

Item Response Models:

o Probabilities can now be computed for the following multidimensional models - M1PL - M2PL - M3PL - MD graded response model - MD partial credit model - MD generalized partial credit model - MD nominal response model - MD multiple-choice model (this model has not been formally introduced in the literature)

o An argument {dimensions} has been added to all the functions that estimate response probabilities

Linking Methods:

o The following multidimensional linking methods have been added - Reckase-Martineau - MD Haebara - MD Stocking-Lord

o For the MD Haebara and MD Stocking-Lord methods there are three dilation options - Oshima-Davey-Lee (estimate all elements of the rotation matrix) - Li-Lissitz (orthogonal rotation with single dilation parameter) - Min (orthogonal rotation with multiple dilation parameters)

Plots:

o Multidimensional surface plots (and conditional surface plots when there are more than two dimensions) can be created

o Vector plots for two-dimensional items can be created

o Argument added for selecting a subset of items

Misc:

o Function read.testfact added for importing item/ability parameters from TESTFACT

o An argument {method} has been added to the link.con function so the linking constants for specific methods can be extraced

o The as.weight function has been simplified and adjusted to compute weights for multiple dimensions

o The display of summary information now has a cleaner look

o All of the .Rd files have been updated to reflect the above changes

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Changes in version: plink_0.1-1

o Data for a set of mixed-format reading tests from a large-scale assessment was added.

o Some additions to the .Rd files

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Changes in version: plink_0.1-0

o Functions read.bilog and read.parscale added for importing item/ability parameters from BILOG and PARSCALE respectively

o Bug fix in the sep.pars function for loc.out = TRUE

o Some corrections/additions to the .Rd files

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Changes in version: plink_0.0-6

o Update to how weights can be computed in the as.weight function

o Some corrections/additions to the .Rd files

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Changes in version: plink_0.0-5

o Corrections made to the output of group names in the plink function

o Correction made to the indexing of group names in the sep.pars function

o Updates to various labels printed by the summary functions

o Some corrections/additions to the .Rd files

o Citation file added

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Changes in version: plink_0.0-4

o The functions link.con, link.pars, and link.ability added for extracting information from the plink output

o Corrections made to the output of group names in the plink function

o Corrections made to the printing of group names in the summary.link function

o Corrections made to the handling of .SavedPlots in th plot.irt.prob function

o The combine.pars function was updated to handle data.frames

o Some corrections/additions to the .Rd files

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Changes in version: plink_0.0-3

o Signature x="list", common="data.frame" was added to the plink function

o Some corrections/additions to the .Rd files

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Changes in version: plink_0.0-2

o A correction to an index variable in the plink function was made (only affects the mcm model)

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Changes in version: plink_0.0-1

o Description was updated

Reference manual

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install.packages("plink")

1.5-1 by Jonathan P. Weeks, 2 years ago


Browse source code at https://github.com/cran/plink


Authors: Jonathan P. Weeks <[email protected]>


Documentation:   PDF Manual  


GPL (>= 2) license


Imports MASS, statmod

Depends on methods, lattice


See at CRAN