knitr::opts_chunk$set( collapse = TRUE, comment = "#>" ) library("conquestr")
This vignette demonstrates how to use conquestr to integrate 'ACER ConQuest' item analysis output into a markdown-based analysis and reporting workflow. In the examples provided we also illustrate how conquestr can support the analyst to visualise and communicate 'ACER ConQuest' test and item analysis in a user-friendly way through various functions for producing conditioanlly formatted tables of statistics that are germane to psychometric analysis.
The basic approach involves using conquestr to read in and process the itanal
objects stored in an 'ACER ConQuest' system file. This workflow can be used when an 'ACER ConQuest' analysis is performed outside of the R environment to produce a system file. It is also easy to extend this workflow to perform end-to-end analysis and reporting by calling 'ACER ConQuest' from with conquestr to produce the relevant system file (see the function ConQuestCall
).
To keep this illustration relatively simple, a short test consisting of 12 multiple-choice items is analysed with a unidimensional Rasch model using Marginal Maximum Likelihood estimation.
conquestr has a built in system file that we will use for this example.
The function getCqItanal
will return a list of lists, each list relating to one generalised item from an 'ACER ConQuest' itanal
output. The list for each item contains the following information: (1) the item name according to the item label, (2) a table of item category statistics for the item, and (3) the item-total and item-rest correlations for the item.
Note that you must use matrixout
in your 'ACER ConQuest' call to itanal
to ensure that these objects are available in the system file from your analysis.
# get default sys file myEx1Sys <- ConQuestSys() # get itanal lists myEx1Sys_itanal <- getCqItanal(myEx1Sys) # show unformatted list objects for first item print(myEx1Sys_itanal[[1]])
Following the item-specific list objects, the last element of the list returned by getCqItanal
contains summary statistics for the full set of items. The summary statistics include raw and latent score distribution statistics and Cronbach's coefficient $\alpha$.
So far, we have shown how to access the test and item analysis statistics that are available through the itanal command in 'ACER ConQuest' and we have shown these without any formatting. One of the many benefits of integrating 'ACER ConQuest' output into a markdown document is to permit automated conditional formatting of item analysis output. In this section we show how this conditional formatting can be set up.
Pre-specifying criteria for conditionally formatting item analysis output is a key step in an automated workflow. Any number of metrics from the item analysis can be specified for conditional formatting. Several of these can be passed to conquestr functions as will be illustrated in the following sections.
# set statistical criteria for conditional formatting easyFlag <- 85 # highlight if facility is GREATER than this value hardFlag <- 15 # highlight if facility is LESS than this value irestFlag <- 0.2 # highlight if item-rest r is LESS than this value underfitFlag <- 1.2 # highlight if weighted MNSQ is GREATER than this value overfitFlag <- 0.8 # highlight if weighted MNSQ is LESS than this value ptBisFlag <- 0.0 # highlight if non-key ptBis r is MORE than this value
The function fmtCqItanal
will return a formated version of the itanal object that we read in earlier. Presently this function will apply coloured text to any distractor point biserial correlation that is larger than r ptBisFlag
. The following example shows the output for the fourth item in the current item analysis.
# return a conditionally formatted item category statistics table for the fourth item myEx1Sys_itanal_f <- fmtCqItanal(myEx1Sys_itanal, ptBisFlag = ptBisFlag, textColHighlight = "red") # print table myEx1Sys_itanal_f[[4]]$table # print summary myEx1Sys_itanal_f[[length(myEx1Sys_itanal_f)]] # the last object is always the summary
This short vignette has illustrated how to access and display itanal output from an 'ACER ConQuest' analysis using conquestr. Future vignettes will demonstrate basic and advanced plotting and the production of publication quality item analysis technical reports.
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.