poly2dich: Change polytomous items to dichotomous item format

In mirt: Multidimensional Item Response Theory

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), sep = "_cat.")

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
sep	character vector pattern to append to each item name in data

Value

Returns an integer matrix

Author(s)

Phil Chalmers [e-mail]

References

Chalmers, R., P. (2012). mirt: A Multidimensional Item Response Theory Package for the R Environment. Journal of Statistical Software, 48(6), 1-29. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.18637/jss.v048.i06")}

Examples

## Not run: 
data(Science)

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

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


## End(Not run)

mirt documentation built on Sept. 11, 2024, 7:14 p.m.