The Power of Statistical Power: the Sample Size in Social Psychology
Giuseppe Mignemi (University of Padova)
The power of a hypothesis test is defined as the probability that the test will reject the null hypothesis, assuming that the null hypothesis is false. Put another way, if an effect is real, what is the probability that an analysis will judge that the effect is statistically significant? (Green & McLeod, 2015). Statistical power always depends on the following three factors: the statistical significance criterion used in the test, the magnitude of the effect of interest, the sample size used to detect the effect. Determining the appropriate sample size can get a bit tricky, but some useful packages are available in R. We will see some easy, but good, computational methods to estimate an appropriate sample size.
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