Contents
How is Epi odds ratio calculated?
The odds ratio is calculated using the number of case-patients who did or did not have exposure to a factor (such as a particular food) and the number of controls who did or did not have the exposure.
Can you get an odds ratio from a chi square test?
An odds ratio is one way, commonly used with 2 x 2 tables, of saying how big the observed difference is. Chi-square test and Odds ratio both can be calculated from case control study and cross-sectional study.
Why can’t you calculate incidence in case control studies?
In a case-control study, you cannot measure incidence, because you start with diseased people and non-diseased people, so you cannot calculate relative risk. Case-control studies are particularly useful when the outcome is rare is uncommon in both exposed and non-exposed people.
What does the odds ratio mean in epidemiology?
Epidemiology – Odds Ratio (OR) OR of > 1 suggests that the odds of exposure are positively associated with the adverse outcome compared to the odds of not being exposed OR of < 1 suggests that the odds of exposure are negatively associated with the adverse outcomes compared to the odds of not being exposed. Potentially,…
What is the significance of the odds ratio?
The further the odds ratio or risk ratio is from 1.0, the stronger the apparent association. Statistical significance can be assessed by p-values for the chi square and Fisher exact tests that are small, <.05; or confidence limits for the odds ratio that do not include 1.0.
How are single 2 x 2 tables used in epidemiology?
The values for one individual cannot be used to predict those for another. Confounding must be removed by stratifying the confounding variables. Single 2 x 2 tables frequently are used in epidemiology to explore associations between exposures to risk factors and disease or other outcomes.
What is the odds ratio of a fish?
Odds Ratio = (a/c) / (b/d) = 2.5/0.3 = 8.33 Interpretation: What does this mean? OR of 1 would suggests that there is no difference between the groups; i.e. there would be no association between the suggested exposure (fish) and the outcome (being ill)