Sample size planning

Sample size calculation is an important prerequisite for planning scientific studies. This presentation will review the statistical basics of how sample size and other factors determine the power of significance tests (bring your laptop to use an online app for the illustration). Afterwards, sample size calculation for standard methods like t-test and regression by means of the R package pwr is illustrated (install R and the pwr package on your laptop to actively follow the example; it is also fine to just watch). In the end, the presentation will discuss critical choices that need to be made for sample size calculation in practice and give a short outlook on sample size calculation for more advanced methods like multilevel models, including some recently proposed methods that are based on machine learning.