Invited Commentary: Self-Control Is a Virtue.

The case-crossover design, introduced in 1991 by Malcolm Maclure (Am J Epidemiol. 1991;133(2):144-153), provided a precise and powerful tool for studying short-term effects of transient triggering exposures on abrupt outcomes like myocardial infarction. The design is an example of "self-control." One compares case-time intervals that include experiences that came just before the health event with control-time intervals that capture comparable experiences more remote from the event. Methodologists have since tweaked the general approach, recognizing issues that need to be considered to guard against time-driven confounders. I discuss opportunities for possible expansion and further mining of the data from this ingenious design. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.