Effect size and power

Content for Friday, October 28, 2022

Content

• Measures of effect size
• Power calculations
• Interplay between sample size, effect and power

Learning objectives

At the end of the session, students should be capable of

• correctly report effect size for common statistics in analysis of variance models
• deduce the sample size necessary to replicate a study at a given power
• explain the interplay between sample size, power and effect size.

Readings

• Chapter 7 of the course notes
• Effect size and power example

Complementary readings

• Lakens (2013)
• Steiger (2004)
• Kelley & Preacher (2012)

Slides

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Tip

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References

Kelley, K., & Preacher, K. (2012). On effect size. Psychological Methods, 17(2), 137–152. https://doi.org/10.1037/a0028086

Lakens, D. (2013). Calculating and reporting effect sizes to facilitate cumulative science: A practical primer for \(t\)-tests and ANOVAs. Frontiers in Psychology, 4, 863. https://doi.org/10.3389/fpsyg.2013.00863

Steiger, J. H. (2004). Beyond the \(F\) test: Effect size confidence intervals and tests of close fit in the analysis of variance and contrast analysis. Psychological Methods, 9, 164–182. https://doi.org/10.1037/1082-989X.9.2.164