[R] Data formatting issue for using sirt package for a Q3 analysis of testlets...?

[nigel daly]

I am having some trouble with setting up a Q3 testlet analysis in R and I was hoping someone may have some advice.


At this link (https://rdrr.io/cran/sirt/man/Q3.testlet.html) there is code for a testlet analysis of 12 items in 4 testlets (although the output has only the 3 categories of A,B, and C....?).


##############

#############################################################################
# EXAMPLE 1: data.read. The 12 items are arranged in 4 testlets
#############################################################################
data<https://rdrr.io/r/utils/data.html>(data.read<https://rdrr.io/cran/sirt/man/data.read.html>)

# Yen's Q3 statistic with testlets
items <- colnames<https://rdrr.io/r/base/colnames.html>(data.read<https://rdrr.io/cran/sirt/man/data.read.html>)
testlet.matrix <- cbind<https://rdrr.io/r/base/cbind.html>( substring<https://rdrr.io/r/base/substr.html>(  items,1,1), items )
mod.testletq3 <- sirt<https://rdrr.io/cran/sirt/man/sirt-package.html>::Q3.testlet<https://rdrr.io/cran/sirt/man/Q3.testlet.html>( q3.res=mod.q3,testlet.matrix=testlet.matrix)
mod.testletq3

##############


My data set consists of 90 items comprising 30 testlets of 3 items per testlet; the are 3 subtests (or levels of difficulty) that contain 10 testlets each. Instructions for the Q3 testlet analysis suggest 2 columns - one with testlet code and the other for item number. So, I formatted the data like so:


[https://lh3.googleusercontent.com/-S5z5wBwaYN52WFl7mES80FI5-a8BQE9Nw5S6aVGUq4F6GUDWhgsRPLQjby4mRgAbJA9xM2YzsQFjcUlrVNlKi2nYJa-drypfZeU4FA0zdmlo_A-GFOOIFNqHQ1P_hsb35jSWcmM]


But after running the code from the above link, the output was still in an A,B,C matrix.


Any advice would be much appreciated.


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Nigel



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