Contrast scores enable you to partition overlapping variance between related abilities or a precursor ability of the construct of interest. In the contrast score name, the first score is the control variable and the second score is the dependent measure. For example, in the Logical Memory Immediate Recall vs. Delayed Recall contrast scaled score, the Logical Memory I scaled score is the control variable and the Logical Memory II scaled score is the dependent measure.
Contrast scaled scores are scaled on a mean of 10 and a standard deviation of 3, but should not be considered a replacement for the standard age-adjusted scaled scores. Contrast scores supplement standard age-adjusted scores and answer specific questions regarding an examinee’s performance. They should not be reported or interpreted as being the examinee’s performance relative to same-age peers.
Continuing with the Logical Memory example, the standard age-adjusted scaled score answers the question, “Is the examinee’s Logical Memory Delayed Recall impaired?” while the contrast score answers the question, “Is the examinee’s Logical Memory Delayed Recall impaired given their initial encoding of the stories during Immediate Recall?” This contrast score reflects the examinee’s performance during delayed recall controlling for performance during immediate recall. In other words, the Logical Memory II scaled score is being adjusted for the Logical Memory I scaled score.
Using the contrast score to supplement the information provided by the standard age-adjusted score, the interpretation of the two scores may be, “Client A’s Logical Memory Delayed Recall is in the Borderline range of functioning in comparison to same age peers. However, given the amount of material initially encoded during Immediate Recall, Client A’s performance is within the Low Average range of functioning.”
Contrast scores between 8 and 12 indicate that performance on the control and dependent variables is not significantly different. For example, the examinee’s delayed recall is what you would expect given their initial encoding of the stories. Contrast scores greater than 12 suggest, for example, that delayed recall is better than expected given their initial encoding of the stories. Contrast scores less than 8 suggest delayed recall is worse than expected given the examinee’s initial encoding of the stories.