On average, the behavioral group gained 8.2 IQ
points, 6.8 points in language comprehension, 11.0
points in expressive language, and 4.4 points on the
communication domain of the VABS. By comparison,
the eclectic group lost 2.9 IQ points, 7.7 points in
language comprehension, 6.4 points in expressive
language, and 4.5 points on the communication
domain on the VABS. The 11-point advantage of
the behavioral group in IQ translates to an Effect Size
estimate of 1.43 (mean difference/pooled standard
deviation), which is considered large for a study
within the behavioral sciences (Cohen, 1988). Similarly,
some writers have viewed gains of this size as
clinically significant (Guralnick, 1998).