While major test publishers randomly select school districts for their national norming studies, a survey of "accepting" and "declining" districts supports the hypothesis that self-selection bias results in overrepresentation of districts which already use a specific publisher's tests or instructional materials. (Author/BW)

The Rasch model for test score equating was compared with three other equating procedures as methods for implementing the norm referenced method (RMC Model A) of evaluating ESEA Title I projects. The Rasch model and its theoretical limitations were described. The three other equating methods used were: linear observed score equating, linear true…