poly2dich: Change polytomous items to dichotomous item format

In xzhaopsy/MIRT: Multidimensional Item Response Theory

Description

Tranforms a matrix of items into a new matrix where the select polytomous items have been converted into comperable 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

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. 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)

xzhaopsy/MIRT documentation built on May 29, 2019, 12:42 p.m.