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Evaluating a Meta-Analysis. Validity Construct validity Internal validity Statistical conclusion validity External validity Theoretical contribution. Construct Validity. Refers to how accurately the theoretical variables being discussed are implemented in a study
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Evaluating a Meta-Analysis • Validity • Construct validity • Internal validity • Statistical conclusion validity • External validity • Theoretical contribution
Construct Validity • Refers to how accurately the theoretical variables being discussed are implemented in a study • Definitions of variables in the effect and moderators should be consistent with the literature • Meta should combine comparable studies • Must consider the construct validity of primary research
Internal Validity • Refers to the validity of causal relations inferred from the results of a study • Moderator analyses only provide correlational information, so causal inferences should be examined critically • Should look for confounds among moderators
Statistical Conclusion Validity • Refers to whether the analytic procedures were performed correctly • Use of fixed vs. random effects models in relation to the inferences being drawn • Assumption of independence • Potentially low power of moderators • Unreliable coding • Uneven distribution among moderator levels • Fishing effects
External Validity • Refers to how well the research captures fundamental aspects of the situation to which you want to draw conclusions • Are the boundaries of the analysis appropriate? • Was the literature search exhaustive? • To what extent did the primary research have strong external validity?
Theoretical Contribution • What implications does the meta have for existing theories? • How novel are the implications? • How broad are the implications? • Are the implications made clear in the presentation? • Are the results from the meta used to support a new theory? • Does the meta-analysis identify new areas for research?
Miller & Pollock’s (1994) Classification of Meta-Analyses • Type A • Summarizes the strength of an effect • Type B • Summarizes the strength of an effect and uses moderator analyses to explain hetereogeneity • Type C • Provides new evidence for a theory by examining variables that have not been manipulated within a study