Articles by R Snippets for IRT

New release – WrightMap 1.2

March 23, 2016 | R Snippets for IRT

A (too long in the making) new version of WrightMap is now available on CRAN (Actually, version 1.2.1 is already up). This new version includes a lot of features that have long been requested, including cut-point lines, alternative item displays (clas...
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WrightMap and TAM – Example continued…

December 29, 2014 | R Snippets for IRT

As a follow up on the previous about integrating the TAM and WrightMap packages, we received a message from one of the TAM developers, Alexander Robitzsch, suggesting that it is possible to generate the Wright Map directly from the MML estimated distribution (instead of using the WLE estimates used in ...
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Using WrightMap with the TAM package

October 24, 2014 | R Snippets for IRT

WrightMap features close integration with Conquest, allowing you to easily read from its output files. However, this is just a nice convenience for Conquest users, as WrightMap was designed to create beautiful item-person plots simply reading standard R matrices; all you need is a matrix of item parameters and a ...
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WrightMap 1.1 Ancillary Antelope Released

April 12, 2014 | R Snippets for IRT

The new version of WrightMap (Ancillary Antelope) is now available on CRAN. Remember that you can visit the package tutorials on our website. This new version includes: - New function to create fit graphs like the example below. - Parameter conversion: Function for calculating Thurstonian thresholds from Master’s deltas. ...
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Wright Map Tutorial – Part 3

March 25, 2014 | R Snippets for IRT

In this part of the tutorial, we’ll show how to load ConQuest output to make a CQmodel object and then WrightMaps. We’ll also show how to turn deltas into thresholds. All the example files here are available in the /inst/extdata folder of the github. If you download ...
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WrightMap Tutorial – Part 2

March 24, 2014 | R Snippets for IRT

Plotting Multidimensional & Polytomous Models Remember: you can find the other parts of the tutorial here: Part 1: Plotting Unidimensional Dichotomous Models Part 3: Using Conquest Output & Making Thresholds Multidimensional models In Part 1, we reviewed how to install the package from GitHub and how to customize unidimensional and dichotomous models. Now in Part 2, ...
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