What’s the right way to A/B test segmentation?

The right way to A/B test segmentation is to create a control group that receives your current segmentation strategy and a test group that receives the new approach, while keeping all other variables constant. You are testing the segmentation logic itself, not the content, send time, or creative.

Randomly split your audience to avoid selection bias. If you are testing engagement based segmentation, divide your list randomly and apply the new segmentation rules to half while maintaining your existing approach for the other half. Measure performance over multiple sends, not a single campaign, because segmentation effects compound over time.

Track engagement metrics, deliverability indicators, and business outcomes such as revenue and conversions. Ensure your sample size is large enough to generate statistically significant results. Small segments produce noisy data that can mislead you. Run the test long enough to account for natural fluctuations, typically at least four to six weeks.

Document what you learn and iterate. Segmentation testing is not a one time event. It is an ongoing process of refinement. Testing segmentation properly is like adjusting your navigation charts based on actual voyage data rather than guessing which route is faster.