pairwise (version 0.2.2)

pairwise.item.fit: Item Fit Indicees

Description

function for calculating item fit indicees

Usage

pairwise.item.fit(pers_obj)

Arguments

pers_obj

an object of class "pers" as a result from function pers

Value

• an object of class c("pairwise_item_fit", "data.frame") contaning item fit indicees.

Details

contrary to many IRT software using Ml based item parameter estimation, pairwise will not exclude persons, showing perfect response vectors (e.g. c(0,0,0) for dataset with three variables), prior to the scaling. Therefor the fit statistics computed with pairwise may deviate somewhat from the fit statistics produced by IRT software using Ml based item parameter estimation (e.g. R-package eRm, depending on the amount of persons with perfect response vectors in the data.

Examples

########
data(sim200x3)
result <- pers(pair(sim200x3))
pairwise.item.fit(pers_obj=result) # item fit statistic