Lecture Conducting and reading research in health and human performance (4/e): Chapter 11 - Ted A. Baumgartner, Larry D. Hensley

Chapter 11 - Meta-analysis. The following will be discussed in this chapter: Meta-analysis, effect size, example size formula, interpretation of ES, steps in meta-analysis, criticism of meta-analysis.

Chapter 11 Meta­Analysis Meta­analysis    Quantitative means of reanalyzing the results from a large number of research studies in an attempt to synthesize findings More than merely a review of related literature Relatively new approach in HHP research Effect Size    Basic statistic used in meta-analysis Converts results from different studies to a common metric so that comparisons can be made Used to estimate meaningfulness of an outcome (i.e., practical significance) – Not influenced by sample size Example Size Formula ES = (Me – Mc)/Sc Formula for estimating ES for difference between experimental and control group Where Me is the mean of the experimental group, Mc is the mean of the control group, and Sc is the standard deviation of the control group Note: There are numerous formulas that can be used to calculate ES Interpretation of ES < 20 small 50 medium > 80 large Source: Cohen (1988) Meta ­Analysis  In meta-analysis, each research study contributes a data point to the subsequent analysis, much like an individual participant in a descriptive or experimental research study Steps in Meta­Analysis Compile references • • Determine inclusive criteria • There must be a substantial number of research studies available on a topic Requires means, standard deviations, correlations, etc be published E.g., published in last 10 years or N > 30 Review each study • • Record information needed to calculate ES from each study Identify and code moderator variables, if any Steps in Meta­Analysis cont Decide which studies to use Do the meta-analysis • • • • Calculate the effect size for each study Generate summary statistics for effect sizes Examine according to moderator variables Interpret results Report the results Criticism of Meta­Analysis     Not the ultimate answer Does not differentiate in quality of studies Combines unlike studies with too much variability (i.e., mixing apples and oranges) Inappropriate coding of variables ... of reanalyzing the results from a large number of research studies in an attempt to synthesize findings More than merely a review of related literature Relatively new approach in HHP research Effect Size... Meta ­Analysis  In meta-analysis, each research study contributes a data point to the subsequent analysis, much like an individual participant in a descriptive or experimental research study Steps in Meta­Analysis... Determine inclusive criteria • There must be a substantial number of research studies available on a topic Requires means, standard deviations, correlations, etc be published E.g., published in