iarm (version 0.4.3)

partgam_DIF: Partial Gamma to detect Differential Item Functioning (DIF)

Description

Items should function in the same way for all subgroups of persons. An item shows differential item functioning (DIF) if there is a significant association between the item score and an exogenous variable, controlling for the scale score. Partial Gamma coefficients are used as test statistics.

Usage

partgam_DIF(
  dat.items,
  dat.exo,
  p.adj = c("BH", "holm", "hochberg", "hommel", "bonferroni", "BY", "none")
)

Value

data frame with Gamma coefficients, standard errors, p values, adjusted p values if an adjustment method has be chosen, and confidence limits for every pair of an item and an exogenous variable.

Arguments

dat.items

A data frame with the responses to the items.

dat.exo

A single grouping factor or a data frame consisting of several exogenous factor variables.

p.adj

Correction method for multiple testing. The methods are "BH","holm", "hochberg", "hommel", "bonferroni", "BY", "none". See p.adjust.

Author

Marianne Mueller

References

Bjorner, J., Kreiner, S., Ware, J., Damsgaard, M. and Bech, P. Differential item functioning in the Danish translation of the SF-36. Journal of Clinical Epidemiology, 51 (11), 1998, pp. 1189-1202.

See Also

partgam_LD

Examples

partgam_DIF(amts[,4:13],amts[,2:3])