5. Measures Of Association And Ch. 3 of E- book Flashcards
How to calculate risk
Number of new cases/ Number at risk
What is the risk ratio
A measure of relative risk and is so-called because it is a ratio of the risk of disease in the exposed group and the risk of disease in the unexposed group .
Calculation for risk ratio
(cases with disease exposed to risk factor(rf))(total exposed to rf) / (cases with disease not exposed to rf) (total not exposed to rf)
How to calculate the odds of an event
Probability of event /
Probability that event does not occur
Equation for odds ratio
(cases with disease exposed to risk f * control not exposed to rf) / (control exposed to rf * cases not exposed to rf)
How to work out odds ratio
odds of those exposed / odds of those not exposed
which studies is relative risk calculated in
Cohort studies
what does it mean when Relative risk = 1
the risk/odds in the exposed group is the same as the risk/odds in the unexposed group. There is indication of neither benefit nor harm.
What does it mean when RR is less than one
When the relative risk is less than one then the exposure is associated with a protective effect.
What does it mean when RR is more than one
When the relative risk is greater than one, then the exposed group have greater risk/odds of contracting the disease, so the expose is associated with harm.
