Regression to the mean or regression to mediocrity is the phenomena of a group’s performance trending closer & closer to the mean over time. This results in small elite groups out performing large elite groups. For instance a small elite group of accountants will often out-perform a Big firm.
This is the reason, small groups often out-perform large groups. At Ellis, we perform better than our larger competitors because we take advantage of Regression to the mean by limiting staff size to 14 or fewer. Actually we notice a fall of in performance over 12. We are certainly one of the best performing firms in the . world, and this is a reason why.