Offers standard errors of prediction and confidence intervals for Vineland Adaptive Behavior Scales (VABS) that help in deciding whether variation in obtained scores of scale administered to the same person more than once is a result of measurement error or whether it reflects actual change in examinee's functional level. Presented values were…

Discusses four ubiquitous major sources of measurement error for individual intelligence scales. Argues that where these sources cannot be directly investigated, they should be estimated rather than ignored. Estimated the typical magnitude of error arising from each of content sampling, time sampling, scoring, and administration. (Author)