How to use MDE Calculator

A Minimum Detectable Effect (MDE) is the minimum uplift you should reach in a given timeline to consider the results of a campaign as statistically significant.

MDE is important in the implementation of an A/B test because it directly influences how long the test needs to run and how large a sample size is required.

The MDE can be calculated using open-source tools, but you can also base it on data calculated directly by AB Tasty.

MDE calculation methods

Manual Calculation

The form

You can manually calculate the MDE of your future experiments by providing data you can have in your third party tools.

You must indicate the following data:

• Total number of visitors of 14 days

• The reference Conversion rate on your primary goal

• The number of variations you want for your future A/B test, in addition to the original

The results

The calculation results are displayed as a graph. Its structure is the same as the AB Tasty Based data calculation.

The value indicated by the curve is the growth you should reach if you want your test to be statistically significant in the given timeline. Considering that, you might ask yourself if you can reach 6.75% growth in 35 days. If it’s not the case, your experiment might not be worth launching.

The next step

After analyzing your MDE results, you can either create a campaign or try another configuration and start the process again.

Use cases

As a CRO manager, I want to build a test on a specific page of my website, but I’m afraid of the time the statistical significance can take to be reached. Therefore, using the MDE will help me understand if I should (or shouldn’t) launch my experiment on that perimeter.