“…However, Type I error is inflated when the anchor set is contaminated by DIF (Stark et al, 2006;Wang & Yeh, 2003) so it is better to designate anchors. Various strategies for empirically identifying anchors have been applied or suggested (Bolt, Hare, Vitale, & Newman, 2004;Edelen, Thissen, Teresi, Kleinman, & Ocepek-Welikson, 2006;Kim & Cohen, 1995;Rensvold & Cheung, 2001;Stark et al, 2006;Wang, 2004;Woods, in press). Many of them are iterative purification procedures wherein the analysis is repeated several times with apparently differentially functioning items removed one by one.…”