Analyzing the Odds Ratio Via Distribution Function

Statistics notes. The odds ratio.

In recent years odds ratios have become widely used in medical reports—almost certainly some will appear in today’s BMJ. There are three reasons for this. Firstly, they provide an estimate (with confidence interval) for the relationship between two binary (“yes or no”) variables. Secondly, they enable us to examine the effects of other variables on that relationship, using logistic regression. ...

Odds Ratio, Hazard Ratio and Relative Risk

Odds ratio (OR) is a statistic commonly encountered in professional or scientific medical literature. Most readers perceive it as relative risk (RR), although most of them do not know why that would be true. But since such perception is mostly correct, there is nothing (or almost nothing) wrong with that. It is nevertheless useful to be reminded now and then what is the relation between the rel...

Prevalence odds ratio v prevalence ratio.

The odds ratio: impact of study design.

In the previous column 1 we considered the “two-by-two” contingency table, a simple square array used to provide a tabular display of the relationship between two categorical variables, each having only two levels. Figure 1 shows such a table, where the rows correspond to nutritional status and the columns correspond to disease status. We showed that the relationship between the two variables c...

A new approximation of the posterior distribution of the log-odds ratio

In this paper, the posterior density of the log-odds ratio is studied. It is assumed that the observations have a multinomial distribution and that the prior on the multinomial parameters is a Dirichlet density. Several approximations currently available are reviewed. When the prior parameters of the Dirichlet density are integers, it is shown that the posterior moments can be computed exactly....