iarm (version 0.1.2)

out_infit: Item Outfit and Infit Statistics

Description

To avoid bias observed item responses are compared to expected responses under the conditional distribution of responses given the total score. This leads to standardized residuals which can be summarized to outfit and infit statistics in the usual way.

Usage

out_infit(object, se = TRUE)

Arguments

object

An object of class "Rm", a fitted Rasch model or partial credit model using the functions RM or PCM in package eRm, or an object of class "pcmodel", a fitted partial credit model using the function pcmodel in package psychotools.

se

If TRUE the standard errors will be included.

Value

an object of class outfit containing:

outfit

outfit statistics

outfit.se

standard errors of outfit statistics

out.pvalue

p values of outfit statistics

infit

infit statistics

infit.se

standard errors of infit statistics

in.pvalue

p values of infit statistics

Details

The fit statistics and their standard errors are calculated as described in Christensen et al. P values are are based on the normal distribution of the standardized fit statistics.

References

Christensen, K. B. , Kreiner, S. & Mesbah, M. (Eds.) Rasch Models in Health. Iste and Wiley (2013), pp. 86 - 90.

Kreiner, S. & Christensen, K. B. (2011) Exact evaluation of Bias in Rasch model residuals. Advances in Mathematics Research, 12, 19-40.

Examples

# NOT RUN {
rm.mod <- RM(amts[,4:13])
out_infit(rm.mod)
# }