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Why are the relative risk and odds ratio approximately equal?
If there’s absolutely no difference between the groups in the probability of an outcome, then both the OR and the RR are 1.0. That’s the only situation in which they can be exactly equal.
How do you interpret and use a relative risk and an odds ratio?
A relative risk or odds ratio greater than one indicates an exposure to be harmful, while a value less than one indicates a protective effect. RR = 1.2 means exposed people are 20% more likely to be diseased, RR = 1.4 means 40% more likely. OR = 1.2 means that the odds of disease is 20% higher in exposed people.
Why is relative risk better than odds ratio?
When the outcome is not rare in the population, if the odds ratio is used to estimate the relative risk it will overstate the effect of the treatment on the outcome measure. The odds ratio will be greater than the relative risk if the relative risk is greater than one and less than the relative risk otherwise.
How do you interpret a relative risk ratio?
A risk ratio greater than 1.0 indicates an increased risk for the group in the numerator, usually the exposed group. A risk ratio less than 1.0 indicates a decreased risk for the exposed group, indicating that perhaps exposure actually protects against disease occurrence.
How do you calculate relative risk ratio?
Relative Risk is calculated by dividing the probability of an event occurring for group 1 (A) divided by the probability of an event occurring for group 2 (B). Relative Risk is very similar to Odds Ratio, however, RR is calculated by using percentages, whereas Odds Ratio is calculated by using the ratio of odds.
Should I use odds ratio or risk ratio?
Be careful of using the risk ratio. An odds ratio is meaningful at any prevalence, but a risk ratio can produce estimates of risk that are greater than 100% in cases where the baseline prevalence is high enough. For example, where the baseline risk is 60% a relative risk of 2 gives a predicted risk of 120%.
When to use relative risk?
Relative Risk (RR) is often used when the study involves comparing the likelihood, or chance, of an event occurring between two groups . Relative Risk is considered a descriptive statistic, not an inferential statistic; as it does not determine statistical significance.
What does relative risk tell us?
Relative risk is the number that tells you how much something you do, such as maintaining a healthy weight, can change your risk compared to your risk if you’re very overweight. Relative risk can be expressed as a percentage decrease or a percentage increase.