Statistical cures and other fallacies.

Relapse rates and thus the impact of therapies have been decreasing. Why they decline and the impact on our ability to understand which treatments are better require more than simple math. The objective of this review is to discuss the impact of regression to the mean, changes in outcome effects and how we compare outcomes over time and among studies. This paper provides discourse on the topics of regression to the mean, some examples of the pitfalls of changes and some difficulties in the interpretation of the common percentage change in outcomes. The results show that we can often be deceived by what we think we see and they also demonstrate how such confusion evolves in the literature. This article aims to caution against the over-interpretation of changes from baseline, which are helped along by regression towards the mean and other factors. Furthermore, how we interpret changes from baseline requires care and not wishful thinking, coupled with careful digestion of seemingly reasonable explications of results.