api {irtoys}R Documentation

The Z3 appropriateness index

Description

Computes the Z3 appropriateness index, a measure of person fit in IRT models

Usage

api(resp, ip)

Arguments

resp A matrix of responses: persons as rows, items as columns, entries are either 0 or 1, no missing data
ip Item parameters: a matrix with one row per item, and three columns: [,1] item discrimination a, [,2] item difficulty b, and [,3] asymptote c.

Value

A vector of length equal to the number of rows in resp, containing the appropriateness indices

Author(s)

Ivailo Partchev

References

Drasgow, F., Levine, M. V., & Williams, E. A. (1985). Appropriateness measurement with polychotomous item response models and standardized indices. British Journal of Mathematical and Statistical Psychology, 38, 67–80

Examples

data(Scored)
p.2pl <- est(Scored, model="2PL", engine="ltm")
api(Scored, p.2pl)

[Package irtoys version 0.1.2 Index]