copyright © allyn & bacon (2010) meta-analysis graziano and raulin research methods: appendix h...
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Copyright © Allyn & Bacon (2010)Copyright © Allyn & Bacon (2010)
Meta-AnalysisMeta-Analysis
Graziano and RaulinGraziano and RaulinResearch Methods: Appendix HResearch Methods: Appendix HThis multimedia product and its contents are protected under copyright law. The following are 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 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 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.part, of any images; (3) Any rental, lease, or lending of the program.
Copyright © Allyn & Bacon (2007)Copyright © Allyn & Bacon (2007)
Meta-AnalysisMeta-Analysis
A statistical way to combine A statistical way to combine several studies on a single topicseveral studies on a single topic
InvolvesInvolves– Computing an effect size for each Computing an effect size for each
studystudy– Computing a weighted effect size for Computing a weighted effect size for
the series of studiesthe series of studies Advances scientific understandingAdvances scientific understanding
Copyright © Allyn & Bacon (2007)Copyright © Allyn & Bacon (2007)
Meta-analysisMeta-analysis
Science builds on its cumulative Science builds on its cumulative knowledgeknowledge
But statistical procedures tend to But statistical procedures tend to discount information from a study discount information from a study if the findings fall short of if the findings fall short of statistical significancestatistical significance
Meta-analysis combines both Meta-analysis combines both significant and non-significant significant and non-significant findingsfindings
Type II ErrorType II Error
Refers to failing to reject a null Refers to failing to reject a null hypothesis that should have been hypothesis that should have been rejectedrejected– Some non-significant statistical tests are Some non-significant statistical tests are
type II errors (due to insufficient power)type II errors (due to insufficient power)– Normally, these non-significant studies are Normally, these non-significant studies are
ignored (that is, never published)ignored (that is, never published) Meta-analysis deals with Type II errors Meta-analysis deals with Type II errors
by including these non-significant by including these non-significant findings in the analysisfindings in the analysis
Copyright © Allyn & Bacon (2010)Copyright © Allyn & Bacon (2010)
Copyright © Allyn & Bacon (2010)Copyright © Allyn & Bacon (2010)
SummarySummary
Meta-analysis statistically combines Meta-analysis statistically combines the results of studies of the same the results of studies of the same phenomenaphenomena
An alternative to the traditional An alternative to the traditional literature reviewliterature review
By objectively summing the effects By objectively summing the effects from all studies, it goes beyond the from all studies, it goes beyond the question of statistical significancequestion of statistical significance