How to Use the Pre/Post Analyzer

1. Enter Summary Data

Input visitors and conversions for the pre-period (before your change) and post-period (after). For revenue analysis, toggle to "Revenue" and add total revenue.

2. Read Results

The calculator auto-computes conversion rates, statistical significance (Z-test), confidence intervals, effect size, and lift. All metrics have i info buttons explaining what they mean.

3. Revenue Mode

When enabled, also compares revenue per visitor, revenue per conversion, and total revenue change.

4. Export

Download a multi-sheet Excel report with all metrics and insights.

Key Difference from A/B Test

A/B tests use randomized concurrent groups. Pre/post compares sequential time periods. Pre/post cannot prove causation because external factors (seasonality, market changes) may explain the difference.