Power & Effect Size -------------------------------------------- **Introduction** *"In plain English, statistical power is the likelihood that a study will detect an effect when there is an effect there to be detected."* ([linked on 6/27/2018][1]) *"The simple definition of effect size is the magnitude, or size, of an effect."* ([linked on 6/27/2018][2]) ------ This is a good place to start for a brief overview and guide to conducting a power analysis: - See [A Researcher’s Guide to Power Analysis (Hunt, n.d.)][3] ------ **Workshop by the Stat Studio** - Associated OSF project - [Effect Size & Power (Link)][4] ------ **Methodology & Applications** - Ethical Technicalities of Sample Size Estimation - [Power, Effect, and Sample Size Using GPower: Practical Issues for Researchers and Members of Research Ethics Committees (Cunningham & McCrum-Gardner, 2007)][5] - Estimating Sample Size in Multilevel Models - [Dancing the Sample Size Limbo with Mixed Models: How Long Can You Go? (Bell, Morgan, Schoeneberger, & Loudermilk, 2010)][6] and [*Introduction to Power and Sample Size in Multilevel Models* (Venkatesan, 2012)][7] - Appropriate Uses of Statistical Power Analyses - [Post Hoc Power, Observed Power, A Priori Power, Retrospective Power, Prospective Power, Achieved Power: Sorting Out Appropriate Uses of Statistical Power Analyses (O'Keefe, 2007)][8] - Guide to understanding and calculating effect sizes as well as methods for calculating confidence intervals and power analysis. - [Effect Size Estimates: Current Use, Calculations, and Interpretation. (Fritz, Morris, & Richler, 2012)][9] - Adjusted versus unadjusted effect sizes. - [To Adjust or Not Adjust: Nonparametric Effect Sizes, Confidence Intervals, and Real-World Meaning. (Ivarsson, Andersen, Johnson, Lindwall, 2013)][10] [1]: https://effectsizefaq.com/2010/05/31/what-is-statistical-power/ [2]: https://researchrundowns.com/quantitative-methods/effect-size/ [3]: http://rgs.usu.edu/irb/wp-content/uploads/sites/12/2015/08/A_Researchers_Guide_to_Power_Analysis_USU.pdf [4]: https://osf.io/z9b2g/ [5]: https://www.semanticscholar.org/paper/Power-,-effect-and-sample-size-using-GPower-:-for-Cunningham-Gardner/532d42418d4ce89ccc38fe688a0b0f6366c511f3 [6]: https://www.researchgate.net/publication/267831991_Dancing_the_Sample_Size_Limbo_with_Mixed_Models_How_Low_Can_You_Go [7]: https://repositories.lib.utexas.edu/handle/2152/ETD-UT-2012-05-5039 [8]: https://www.tandfonline.com/doi/abs/10.1080/19312450701641375 [9]: https://www.ncbi.nlm.nih.gov/pubmed/21823805 [10]: https://www.sciencedirect.com/science/article/pii/S1469029212000945