sirt: dif.strata.variance – R documentation

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sirt

dif.strata.variance

Stratified DIF Variance

Description

Calculation of stratified DIF variance

Usage

dif.strata.variance(dif, se.dif, itemcluster)

Arguments

`dif`	Vector of uniform DIF effects
`se.dif`	Standard error of uniform DIF effects
`itemcluster`	Vector of item strata

Value

A list with following entries:

`stratadif`	Summary statistics of DIF effects within item strata
`weighted.DIFSD`	Weighted DIF standard deviation
`unweigted.DIFSD`	DIF standard deviation

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.