The A/B Test That Peeked Too Early

Through day 3, variant B's cumulative conversion rate (9%) looks like a decisive win over variant A's 5% — nearly double. Running the cumulative rate out to the full 14-day test shows B's early lead was a novelty spike that fades: by day 14, B has fallen to 4.68% while A held a steady 5.00% the entire time. The day-3 leader completely reverses by the end of the test.