Blog Archives

WrightMap: Multifaceted models

January 7, 2015
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WrightMap: Multifaceted models

We received an email from a user who was interested in displaying results from a multifaceted model in WrightMap. In the WrightMap manual, we show how to use multifaceted results from ConQuest: fpath <- system.file("extdata", package = "WrightMap") model4 <- CQmodel(file.path(fpath, "ex4a.mle"), file.path(fpath, "ex4a.shw")) wrightMap(model4, item.table = "rater", interactions = "rater*topic", step.table = "topic") (See this tutorial for more details.) But...

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WrightMap and TAM – Example continued…

December 29, 2014
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WrightMap and TAM – Example continued…

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 the previous post). Let’s start with the same setup: library(TAM) library(WrightMap) data( sim.rasch...

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Using WrightMap with the TAM package

October 24, 2014
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Using WrightMap with the TAM package

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 matrix of person estimates and you can start creating...

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WrightMap 1.1 Ancillary Antelope Released

April 12, 2014
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WrightMap 1.1 Ancillary Antelope Released

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. New examples. Added axis...

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WrightMap 1.1 Ancillary Antelope Released

April 12, 2014
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WrightMap 1.1 Ancillary Antelope Released

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. - New examples. - Added axis range controls. - Made histogram...

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Wright Map Tutorial – Part 3

March 25, 2014
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Wright Map Tutorial – Part 3

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 the latest version of the package, they should be in a folder...

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Wright Map Tutorial – Part 3

March 25, 2014
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Wright Map Tutorial – Part 3

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 the latest version of the package, they should be in a folder...

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WrightMap Tutorial – Part 2

March 24, 2014
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WrightMap Tutorial – Part 2

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, we’ll look at graphing some...

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Recoding Polytomous Items with Missing Categories

December 26, 2012
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This function helps prepare data for analysis with models that require polytomous items to be coded from 0 to N without missing categories, such as the Partial Credit Model (Masters, 1982). When there are no missing categories, an item that was suppos...

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Simple data simulator for the 2PL model

December 21, 2012
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The function: This is a very simple data simulator for a 2PL Model. This is just to get you started, from here is easy to add function parameters for indicating item locations and slopes or person distribution characteristics. The function accepts on...

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