Do Case-Control Studies Always Estimate Odds Ratios?

An Estimate of the Odds Ratio That Always Exists

This article proposes an estimate of the odds ratio in a (2 £ 2) table obtained from studies in which the row totals are Ž xed by design, such as a phase II clinical trial. Our estimate,basedon themedianunbiasedestimateof the probabilitiesof success in the (2£2) table, will always be in the interval (0;1): Another estimate of the odds ratio which has such properties is obtained when adding .5 t...

Estimating crude or common odds ratios in case-control studies with informatively missing exposure data.

In case-control studies, the crude odds ratio derived from a 2 x 2 table and the common odds ratio adjusted for stratification variables are staple measures of exposure-disease association. While missing exposure data are encountered in the majority of such studies, formal attempts to deal with them are rare, and a complete-case analysis is the norm. Furthermore, the probability that exposure i...

What do case-control studies estimate? Survey of methods and assumptions in published case-control research.

To evaluate strategies used to select cases and controls and how reported odds ratios are interpreted, the authors examined 150 case-control studies published in leading general medicine, epidemiology, and clinical specialist journals from 2001 to 2007. Most of the studies (125/150; 83%) were based on incident cases; among these, the source population was mostly dynamic (102/125; 82%). A minori...

Making sense of odds and odds ratios.

Odds and odds ratios are hard for many clinicians to understand. Odds are the probability of an event occurring divided by the probability of the event not occurring. An odds ratio is the odds of the event in one group, for example, those exposed to a drug, divided by the odds in another group not exposed. Odds ratios always exaggerate the true relative risk to some degree. When the probability...

Mischievous Odds Ratios