Odds ratio (AD/BC) is the ratio between number of times that something happens and does not happen.

Crude odds ratio is the ratio that is not stratified (ex. by age).

Adjusted odds ratio is a stratified odds ratio. If the odds ratio equals one, then there is no association, and null hypothesis shall be accepted. If one is included into confidence interval, then it is possible that odds ratio equals one, and it is not statistically significant.

If stratified odds ratios are about the same, or there are no significant differences, the odds ratios are combined into one common odds summary estimate of two stratum specific ORs using Mantel-Haenszel and/or Cohran's tests, or multivariable analysis.

A crude odds ratio is the probability that a case preceeded the control in regard to exposure and history.

A crude odds ratio is the probability that a case preceeded the control in regard to exposure and history.

An odds ratio is the difference between the number of times that something happens and does not happen. An unadjusted odds ratio is a guess between what could or could not happen.

odds ratio.