Mahdollisuussuhde

Mahdollisuussuhde, often translated as odds ratio, is a statistical measure used in observational studies and surveys to estimate the strength of association between an exposure and an outcome. It is particularly common in case-control studies. The odds ratio is calculated by dividing the odds of exposure in the group with the outcome by the odds of exposure in the group without the outcome. Alternatively, it can be calculated by dividing the odds of the outcome in the exposed group by the odds of the outcome in the unexposed group.

An odds ratio of 1 indicates that the odds of the outcome are the same for both exposed and unexposed groups, suggesting no association. An odds ratio greater than 1 suggests that the odds of the outcome are higher in the exposed group, indicating a positive association. Conversely, an odds ratio less than 1 suggests that the odds of the outcome are lower in the exposed group, indicating a negative association or a protective effect.

It is important to note that the odds ratio is an estimate of the relative risk, especially when the outcome is rare. In such cases, the odds ratio closely approximates the relative risk. However, when the outcome is common, the odds ratio can deviate significantly from the relative risk. The interpretation of the odds ratio should always consider the study design and the characteristics of the study population. Confidence intervals are typically reported alongside the odds ratio to indicate the precision of the estimate.