dif.variance: DIF Variance

In sirt: Supplementary Item Response Theory Models

DIF Variance

Description

This function calculates the variance of DIF effects, the so called DIF variance (Longford, Holland & Thayer, 1993).

Usage

dif.variance(dif, se.dif, items=paste("item", 1:length(dif), sep="") )

Arguments

dif	Vector of uniform DIF effects
se.dif	Standard error of uniform DIF effects
items	Optional vector of item names

Value

A list with following entries

weighted.DIFSD	Weighted DIF standard deviation
unweigted.DIFSD	DIF standard deviation
mean.se.dif	Mean of standard errors of DIF effects
eb.dif	Empirical Bayes estimates of DIF effects

References

Longford, N. T., Holland, P. W., & Thayer, D. T. (1993). Stability of the MH D-DIF statistics across populations. In P. W. Holland & H. Wainer (Eds.). Differential Item Functioning (pp. 171-196). Hillsdale, NJ: Erlbaum.

See Also

See dif.logistic.regression for examples.

sirt documentation built on May 29, 2024, 8:43 a.m.