Test Positive Calculator

This app helps you interpret multiple conflicting test results.

If you have multiple test results of limited accuracy, this is the app that will help you interpret it.

Test Positive Calc is a risk calculator app that calculates the probability of having a condition even when multiple tests are taken by using the number of tests that are positive, the number of tests taken, the accuracy of the tests (false positive and negative rates) and the prevalence of the condition being tested (current positivity).

When opening the app, the accuracy and prevalence values will already be entered. The accuracy comes from a study on rapid tests while the prevalence comes from United States pandemic data assuming that the user is connected to the internet. The prevalence or current positivity is treated as the likelihood of having the condition without knowing the test results. You may change this value along with the accuracy values to anything you like in order to match the desired condition to be tested and play with the numbers to see how the probability changes.

This app was inspired by the fact that many tests are not completely accurate. Therefore, one can take multiple tests and calculate the likelihood of being positive to make appropriate risk assessments. This app does the calculations for you.

You can read this paper to learn more about the math behind the app: https://drive.google.com/file/d/12RuZqj79QkBG87OVmYcgvyff86vgLxDd/view?usp=sharing