Enter the prevalence in the test group and the prevalence in the control group into the Prevalence Ratio Calculator. The calculator will evaluate and display the Prevalence Ratio.

## Prevalence Ratio Formula

The following formula is used to calculate the Prevalence Ratio.

PR = PT / PC

- Where PR is the Prevalence Ratio ( )
- PT is the prevalence in test group
- PC is the prevalence in control group

To calculate the prevalence ratio, divide the prevalence in the test group by the prevalence in the control group.

## How to Calculate Prevalence Ratio?

The following example problems outline how to calculate Prevalence Ratio.

Example Problem #1:

- First, determine the prevalence in test group.
- The prevalence in test group is given as: .75.

- Next, determine the prevalence in control group.
- The prevalence in control group is provided as: .90.

- Finally, calculate the Prevalence Ratio using the equation above:

PR = PT / PC

The values given above are inserted into the equation below and the solution is calculated:

PR = .75 / .90 = .833

Example Problem #2:** **

For this problem, the variables required are provided below:

prevalence in test group = .60

prevalence in control group = .50

Test your knowledge using the equation and check your answer with the calculator above.

PR = PT / PC** = ?**