For example, if adding the polygenic score to the set of control variables in an RCT increases their joint explanatory power from 10% to 20%, then the gain in power from including the polygenic score is equivalent to increasing the RCT’s sample size by 11% (for such calculations, see the SOM of Rietveld et al.4). Third, the polygenic scores can be used as a tool for exploring gene-environment interactions32, which are known to be important for genetic effects on educational attainment and cognitive performance1,33.
