data(iqitems)
This data set and the associated data set (ability
based upon scoring these multiple choice items and converting them to correct/incorrect may be used to demonstrate item response functions, tetrachoric
correlations, or irt.fa
as well as omega
estimates of of reliability and hierarchical structure.
In addition, the data set is a good example of doing item analysis to examine the empirical response probabilities of each item alternative as a function of the underlying latent trait. When doing this, it appears that two of the matrix reasoning problems do not have monotonically increasing trace lines for the probability correct. At moderately high ability (theta = 1) there is a decrease in the probability correct from theta = 0 and theta = 2.
Condon, David and Revelle, William, (2014) The International Cognitive Ability Resource: Development and initial validation of a public-domain measure. Intelligence, 43, 52-64.
data(iqitems)
iq.keys <- c(4,4,4, 6, 6,3,4,4, 5,2,2,4, 3,2,6,7)
score.multiple.choice(iq.keys,iqitems) #this just gives summary statisics
#convert them to true false
iq.scrub <- scrub(iqitems,isvalue=0) #first get rid of the zero responses
iq.tf <- score.multiple.choice(iq.keys,iq.scrub,score=FALSE)
#convert to wrong (0) and correct (1) for analysis
describe(iq.tf)
#see the ability data set for these analyses
#now, for some item analysis
#iq.irt <- irt.fa(iq.tf) #do a basic irt
#iq.sc <-score.irt(iq.irt,iq.tf) #find the scores
#op <- par(mfrow=c(4,4))
#irt.responses(iq.sc[,1], iq.tf)
#op <- par(mfrow=c(1,1))
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