The WJ IV provides two primary methods for comparing tests or cluster scores. One is based on a predictive model (the variation and comparison procedures) and the other allows comparisons of SEM confidence bands, which takes into account each measures reliability. A third method for comparing scores, one that takes into account the correlation between compared measures (ability cohesion model) is not provided, but is frequently used by assessment professionals. The three types of score comparison methods are described and new information, via a "rule of thumb" summary slide and nomograph, are provided to allow WJ IV users to evaluate scores via all three methods.
A PDF copy of the key WJ IV base rate rule-of-thumb slide can be found here.
A PDF copy of the key WJ IV base rate rule-of-thumb slide can be found here.
