# 2.1.2.3. The confidence intervals for relative risk

The Confidence Intervals for Relative Risk can be calculated using the equation given in Equation 2.1.2.3.

There are numerous online RR calculators (e.g. http:// faculty.vassar.edu/lowry/VassarStats.html). Common statistical packages often give RR and associated CI when performing tests on 2x2 contingency tables. Caution should be used, however, to ensure that the data entered in such packages are in keeping with the layout presented in Table 3.

**Table 3. **Structure of data for calculation of Relative Risk. Both disease outcome and risk factor exposure are dichotomous.