Application and evaluation of quantitative meta-analytic techniques (particularly, meta-analytic structural equation modeling and single-case research designs' synthesis). Quantitative meta-analysis is used in social, medical and behavioral sciences to statistically summarize results - effect sizes - from studies examining common phenomena. The technique allows for exploration of sources of heterogeneity in effects by examining the extent to which characteristics of studies and samples might lead to differences in effects. Meta-analysis offers challenges that provide rich opportunities for methodological research.