This function calculates the variance of DIF effects, the so called DIF variance (Longford, Holland & Thayer, 1993).
dif.variance(dif, se.dif, items=paste("item", 1:length(dif), sep="") )
Vector of uniform DIF effects
Standard error of uniform DIF effects
Optional vector of item names
A list with following entries
Weighted DIF standard deviation
DIF standard deviation
Mean of standard errors of DIF effects
Empirical Bayes estimates of DIF effects
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 dif.logistic.regression
for examples.