ERIC Number: EJ1256749
Record Type: Journal
Publication Date: 2017-Mar
Pages: 14
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-1759-2879
EISSN: N/A
Basics of Meta-Analysis: "I"[superscript 2] Is Not an Absolute Measure of Heterogeneity
Borenstein, Michael; Higgins, Julian P. T.; Hedges, Larry V.; Rothstein, Hannah R.
Research Synthesis Methods, v8 n1 p5-18 Mar 2017
When we speak about heterogeneity in a meta-analysis, our intent is usually to understand the substantive implications of the heterogeneity. If an intervention yields a mean effect size of 50 points, we want to know if the effect size in different populations varies from 40 to 60, or from 10 to 90, because this speaks to the potential utility of the intervention. While there is a common belief that the "I"[superscript 2] statistic provides this information, it actually does not. In this example, if we are told that "I"[superscript 2] is 50%, we have no way of knowing if the effects range from 40 to 60, or from 10 to 90, or across some other range. Rather, if we want to communicate the predicted range of effects, then we should simply report this range. This gives readers the information they think is being captured by "I"[superscript 2] and does so in a way that is concise and unambiguous.
Descriptors: Meta Analysis, Effect Size, Intervention, Prediction, Outcomes of Treatment, Statistical Analysis, Medical Research
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Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
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Language: English
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