THE IMPORTANCE OF CONTENT REPRESENTATION FOR COMMON-ITEM EQUATING WITH NONRANDOM GROUPS

The equating accuracy of content-representative anchors versus nonrepresen-tative but substantially longer anchors is compared. Content representation was defined as a match between anchors and total test of the percentage of items in each of several content areas. Through a chain of equatings it was found that content representation in anchors was critical for the testing program studied. The results are explained in terms of differences in mean profiles (by content area) of the nonrandom groups used for equating.