# Relative Risk

Relative Risk

In statistics and mathematical epidemiology, relative risk (RR) is the risk of an event (or of developing a disease) relative to exposure. Relative risk is a ratio of the probability of the event occurring in the exposed group versus a non-exposed group.

Risk Disease status
Present Absent
Smoker
Non-smoker

Consider an example where the probability of developing lung cancer among smokers was 20% and among non-smokers 1%. This situation is expressed in the 2 × 2 table to the right.

Here, a = 20, b = 80, c = 1, and d = 99. Then the relative risk of cancer associated with smoking would be

Smokers would be twenty times as likely as non-smokers to develop lung cancer.

Another term for the relative risk is the risk ratio because it is the ratio of the risk in the exposed divided by the risk in the unexposed.

### Other articles related to "risk, relative risk, risks":

Control Event Rate - Worked Example
... Another worked example is as follows Example 1 risk reduction Example 2 risk increase Experimental group (E) Control group (C) Total (E) (C) Total Events (E. 1 Example 2 CER − EER < 0 absolute risk reduction ARR (−)0.3, or (−)30% N/A > 0 absolute risk increase ARI N/A 0.1, or 10% (CER − EER) / CER < 0 relative risk ...
Absolute Risk Reduction - Worked Example
... Example 1 risk reduction Example 2 risk increase Experimental group (E) Control group (C) Total (E) (C) Total Events (E) EE = 15 CE = 115 ... EE = 75 CE = 175 ... Non-e ... Example 1 Example 2 CER − EER < 0 absolute risk reduction ARR (−)0.3, or (−)30% N/A > 0 absolute risk increase ARI N/A 0.1, or 10% (CER − EER ...
Attributable Risk - Worked Example
... Example 1 risk reduction Example 2 risk increase Experimental group (E) Control group (C) Total (E) (C) Total Events (E) EE = 15 CE = 115 ... EE = 75 CE ... Example 1 Example 2 CER − EER < 0 absolute risk reduction ARR (−)0.3, or (−)30% N/A > 0 absolute risk increase ARI N/A 0.1, or 10% (CER − EER) / CER < 0 relative risk reduction RRR (−)0.75 ...
Abortion–breast Cancer Hypothesis - Epidemiological Studies - Interviews - Daling
1994 study (845/961 ABC cases/controls) results indicated an associated relative risk of 1.5 (1.2 – 1.9) among women who had given birth before having an abortion ... This was reflected in higher risks for women younger than 18 or older than 30 years of age who have had abortions after 8 weeks' gestation ... found that abortion was associated with a relative risk value of 1.2 (1.0 – 1.5) ...

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