The case-crossover design uses cases only, and compares exposures just prior to the event times to exposures at comparable control, or "referent" times, in order to assess the effect of short-term exposure on the risk of a rare event. It has commonly been used to study the effect of air...

The case-crossover design has been widely used to study the association between short term air pollution exposure and the risk of an acute adverse health event. The design uses cases only, and compares exposure at the event time with exposure at other control or "referent" times. By making...

A marker that is strongly associated with outcome (or disease) is often assumed to be effective for classifying individuals according to their current or future outcome. However, for this to be true, the associated odds ratio must be of a magnitude rarely seen in epidemiological studies. An...