Building validity evidence for scores on a state-wide alternate assessment: A contrasting groups, multimethod approach

The relationships between ratings on the Idaho Alternate Assessment (IAA) for 116 students with significant disabilities and corresponding ratings for the same students on two norm-referenced teacher rating scales were examined to gain evidence about the validity of resulting IAA scores. To contextualize these findings, another group of 54 students who had disabilities, but were not officially eligible for the alternate assessment also was assessed. Evidence to support the validity of the inferences about IAA scores was mixed, yet promising. Specifically, the relationship among the reading, language arts, and mathematics achievement level ratings on the IAA and the concurrent scores on the ACES-Academic Skills scales for the eligible students varied across grade clusters, but in general were moderate. These findings provided evidence that IAA scales measure skills indicative of the state's content standards. This point was further reinforced by moderate to high correlations between the IAA and Idaho State Achievement Test (ISAT) for the not eligible students. Additional evidence concerning the valid use of the IAA was provided by logistic regression results that the scores do an excellent job of differentiating students who were eligible from those not eligible to participate in an alternate assessment. The collective evidence for the validity of the IAA scores suggests it is a promising assessment for NCLB accountability of students with significant disabilities. The methods of establishing this evidence have the potential to advance validation efforts of other states' alternate assessments.