Meta-Analysis and the Planning of Future Studies
A recent meta-analysis on ability grouping by Kulik and Kulik (1982) was used as an example to demonstrate how a researcher might plan for adequate sample sizes and power in future research. Data sufficient to estimate minimum sample sizes and power were gleaned from the meta-analysis study or obtained from its authors. Distributions of harmonic mean sample size and estimated power were displayed and ranges of estimates for each were presented using effect sizes from the meta-analysis with fixed alpha. Although effect sizes were relatively symmetric about .10, power and harmonic mean sample sizes were quite skewed. Recommendations for major professors, re- searchers and journal editors were made to assist in the evaluation and planning of research.