title: Meta-Analysis With Complex Research Designs: Dealing With Dependence From Multiple Measures and Multiple Group Comparisons.
abstract: Previous research has shown that treating dependent effect sizes as independent inflates the variance of the mean effect size and introduces bias by giving studies with more effect sizes more weight in the meta-analysis. This article summarizes the different approaches to handling dependence that have been advocated by methodologists, some of which are more feasible to implement with education research studies than others. A case study using effect sizes from a recent meta-analysis of reading interventions is presented to compare the results obtained from different approaches to dealing with dependence. Overall, mean effect sizes and variance estimates were found to be similar, but estimates of indexes of heterogeneity varied. Meta-analysts are advised to explore the effect of the method of handling dependence on the heterogeneity estimates before conducting moderator analyses and to choose the approach to dependence that is best suited to their research question and their data set.
authors.affiliation: Nancy Scammacca, PhD, is a research associate at the Meadows Center for Preventing Educational Risk in the College of Education at the University of Texas at Austin, 1 University Station D4900, Austin, TX 78712.
authors.forename: Nancy
authors.initials: N
authors.lastname: Scammacca
authors.affiliation: Greg Roberts, PhD, is the director of the Vaughn Gross Center for Reading and Language Arts and the associate director of the Meadows Center for Preventing Educational Risk at the University of Texas at Austin.
authors.forename: Greg
authors.initials: G
authors.lastname: Roberts
authors.affiliation: Karla K. Stuebing, PhD, is a research professor at the Texas Institute for Measurement, Evaluation, and Statistics at the University of Houston.
authors.forename: Karla K
authors.initials: KK
authors.lastname: Stuebing
keywords: heterogeneity analysis; meta-analysis; statistical dependence