Meta-Analysis of the Pattern of Change in IQ Scores over a Three-Year Period for Exceptional Children with LD, EBD, and MR

The techniques of meta-analysis were used to arrive at a quantitative synthesis of the results of 39 samples, based on the retesting of exceptional children using the WISC-R or WISC-III over an average time interval of three years. The primary findings indicated that IQ scores do change over time, and that the patterns of change for FSIQ, VIQ, and PIQ vary as a function of disability group. On average, children with LD and MR scored 2 points lower on retested VIQ, while retested PIQ increases significantly for LD and EBD children. Moreover, several factors including age, ability level, retest interval, and test version were found to be meaningful moderating factors which affect the variability of effect sizes for learning-disabled children. Further implications were also discussed.