mirt (version 1.33.2)

poly2dich: Change polytomous items to dichotomous item format

Description

Transforms a matrix of items into a new matrix where the select polytomous items have been converted into comparable dichotomous items with the same information.

Usage

poly2dich(data, which.items = 1:ncol(data))

Arguments

data

an object of class data.frame or matrix

which.items

a vector indicating which items should be transformed into the dichotomous form. Default uses all input items

Value

Returns an integer matrix

References

Chalmers, R., P. (2012). mirt: A Multidimensional Item Response Theory Package for the R Environment. Journal of Statistical Software, 48(6), 1-29. 10.18637/jss.v048.i06

Examples

# NOT RUN {
# }
# NOT RUN {
data(Science)

head(Science)
newScience <- poly2dich(Science)
head(newScience)

newScience2 <- poly2dich(Science, which.items = 2)
head(newScience2)

# }
# NOT RUN {
# }