Data Flashcards
What is relative risk?
the ratio of the probability of an outcome in an exposed group compared to the probability of an outcome in an unexposed group
What is odds ratio?
ratio of the odds of the outcome in people with the exposure compared to the odds of the outcome in people without the exposure.
What is the difference between probability and odds?
Probability: 1/n
Odds: 1/n-1
When is RR used?
- to compare the risk of an adverse outcome when receiving a medical treatment versus no treatment (or placebo)
- when exposed to an environmental risk factor versus not exposed
What is the difference of OR and RR?
OR is calculated by using the ratio of odds whereas RR is calculated by using probabilities (usually expressed as percentages)
What is the denominator of odds?
odds of the outcome in people unexposed
What is the numerator of RR?
the probability of the event (or outcome) occurring in an exposed group
What does a RR=1 mean?
exposure is not associated with the outcome
What does a RR<1 mean?
risk of the outcome is decreased by the exposure
What does a RR>1 mean?
risk of the outcome is increased by the exposure
What does a OR=1 mean?
Exposure does not affect the odds of the outcome
What does a OR<1 mean?
Exposure associated with lower odds of the outcome
What does a OR>1 mean?
Exposure associated with higher odds of the outcome
When can OR be used as an estimate of the RR?
rare events
When is OR used?
OR is useful for a capturing the rare side effect
