MetaAnalysis Graziano and Raulin Research Methods Appendix H

Meta-Analysis Graziano and Raulin Research Methods: Appendix H This multimedia product and its contents are protected under copyright law. The following are prohibited by law: (1) Any public performance or display, including transmission of any image over a network; (2) Preparation of any derivative work, including the extraction, in whole or in part, of any images; (3) Any rental, lease, or lending of the program. Copyright © Allyn & Bacon (2010)

Meta-Analysis A statistical way to combine several studies on a single topic n Involves n – Computing an effect size for each study – Computing a weighted effect size for the series of studies n Advances scientific understanding Copyright © Allyn & Bacon (2007)

Meta-analysis Science builds on its cumulative knowledge n But statistical procedures tend to discount information from a study if the findings fall short of statistical significance n Meta-analysis combines both significant and non-significant findings n Copyright © Allyn & Bacon (2007)

Type II Error n Refers to failing to reject a null hypothesis that should have been rejected – Some non-significant statistical tests are type II errors (due to insufficient power) – Normally, these non-significant studies are ignored (that is, never published) n Meta-analysis deals with Type II errors by including these non-significant findings in the analysis Copyright © Allyn & Bacon (2010)

Summary n n n Meta-analysis statistically combines the results of studies of the same phenomena An alternative to the traditional literature review By objectively summing the effects from all studies, it goes beyond the question of statistical significance Copyright © Allyn & Bacon (2010)