First, by examining associations between the scores and high-quality measures of endophenotypes, researchers may be able to disentangle the mechanisms by which genetic factors affect EA and cognitive phenotypes. Such studies are already being conducted with polygenic scores from earlier GWAS of EA6,7, but they can now be well powered in samples as small as those from laboratory experiments. For example, if our polygenic score explains 10% of the variance in an endophenotype, then its effect can be detected at a 5% significance threshold with 80% power in a sample of only 75 individuals. Second, the polygenic scores can be used as control variables in randomized controlled trials (RCTs) of interventions that aim to improve academic and cognitive outcomes. Given the scores’ current levels of predictive power, such use can now generate non-trivial gains in statistical power for the RCT. 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
