This post is almost entirely inaccurate re: actual statistics. Power, as you say, is the likelihood of a given experiment rejecting the null hypothesis given some a priori sample size and effect size. And one- vs. two-tailed tests do not change effect sizes, or even your estimate of the variability surrounding an effect, but a p-value related to the effect (should you choose to calculate one).<p>You would think, given their team of &quot;analysts&quot; and &quot;statisticians&quot;, that they might have known these basic pieces of statistics.