Relative Risk Calculator
Posted by Dinesh onThis calculator calculates the relative risk using variable present, reference values.
Relative Risk Outcome
| Yes | No | |
| Variable Present (Yes) | a | b |
| Variable not Present or reference (No) | c | d |
Relative Risk Calculation
Formula:
Relative Risk = (a ÷ a+b) / (c ÷ c+d)
Where,a, b = Variable Present(Yes)
c, d = Variable not Present or reference (No)
Example
| Yes | No | |
| Variable Present (Yes) | 9 | 1 |
| Reference (No) | 2 | 8 |
In this example, 9 of the 10 pairs of sneakers that were worn without socks were smelly, and 2 of the 10 pairs of sneakers worn with socks were smelly. The relative risk would be (9/10) / (2/10), or 4.5. Therefore, the data suggest it is four times more likely to have smelly shoes if shoes are worn without socks.
Things to note about this formula:
- If the relative risk < 1 the exposure/incidence is protective: it lowers the risk for expressing the outcome.
- If the relative risk = 1 there is no association between an exposure that delineates the cohorts and the outcome.
- If the relative risk > 1 there is an association between an exposure that delineates the cohorts and the outcome (as seen in the example).