Survey research and design in psychology/Lectures/Power & effect sizes

This page is complete for 2013.

Lecture 09: Power & effect sizes

Resource type: this resource contains a lecture or lecture notes.

This is the ninth lecture for the Survey research and design in psychology unit of study.

Outline

Explains use of, and issues involved in,

1. significance testing
2. inferential decision making
3. statistical power
4. effect sizes
5. confidence intervals
6. publication bias
7. academic integrity

in the social sciences.

Conclusions

• Decide on H₀ and H₁ (1 or 2 tailed)
• Calculate power beforehand and adjust the design to detect a minimum effect size (ES)
• Report statistical power, statistical significance, ES, confidence interval
• Compare results with meta-analyses and/or meaningful benchmarks
• Take a balanced, critical approach, striving for objectivity and academic integrity

Readings

1. Howitt, D. & Cramer, D. (2011). The size of effects in statistical analysis: Do my findings matter? (Ch. 34). In Introduction to statistics in psychology (5th ed; pp. 419-425). Harlow, UK: Pearson.
2. Howitt, D. & Cramer, D. (2011). Meta-analysis: Combining and exploring statistical findings from previous research (Ch. 35). In Introduction to statistics in psychology (5th ed; pp. 426-441). Harlow, UK: Pearson.
3. Howitt, D. & Cramer, D. (2011). Confidence intervals (Ch. 37). In Introduction to statistics in psychology (5th ed; pp. 455-464). Harlow, UK: Pearson.
4. Howitt, D. & Cramer, D. (2011). Statistical power (Ch. 39). In Statistical power: Getting the sample size right (5th ed; pp. 486-507). Harlow, UK: Pearson.
5. Wilkinson, L., & APA Task Force on Statistical Inference. (1999). Statistical methods in psychology journals: Guidelines and explanations. American Psychologist, 54, 594-604.

Handout

• 2013 handouts:
  • Download 6 slides to a page:
  • Download 3 slides to a page: -->

Recordings

These are the 2013 lecture recordings:

• echo360 (rich media)
• mpv (video)
• mp3 (audio)

See also

• Multiple linear regression II (Previous lecture)
• Summary & conclusion (Next lecture)
• Funnel plot (Wikipedia)

External links

• Lecture slides (slideshare)
• p values and statistical significance (A New View of Statistics]
• Statistical power analysis quiz (Practice) (Howitt & Cramer, 2011)