LC/OE QUESTION: Should scores on the OWLS, PLS-3, and CELF-Preschool be comparable?
Scores on the OWLS are very likely to be higher than those on the other two instruments. There is a valid reason for the difference in scores. Both CELF-Preschool and PLS-3 use a truncated sample-that is, they do not include any children with identified language disabilities in their standardization sample. The OWLS is based on a nationally representative normative sample, which includes special education students in approximately the same percentages that they occur in the general population. So you can see how students would score lower on a test with a truncated sample than on a test with representative norms. You may be interested in an article in the ASHA journal Language, Speech, and Hearing Services in Schools (Volume 27, Number 1, January 1996) entitled “Creating Language Impairments in Typically Achieving Children: The Pitfalls of ‘Normal’ Normative Sampling” by Teresa Ukrainetz McFadden. Many school districts are now insisting that testing be done with assessments based on re
