Professional Football Participation and Mortality

To the Editor A well-defined exposure is essential for a cohort study to determine an association between the exposure and a specific outcome. A lower-dose exposure is only useful and statistically powerful when used to examine a dose-response relationship; used only as a control, it is likely to underestimate an association. An infamous example of misclassification of exposed and nonexposed groups and a subsequent null result was the Danish study assessing risk of brain tumors from mobile phones.
Source: JAMA - Category: General Medicine Source Type: research