Community night · March
Does one extra reminder 24h before the doors open move attendance?
95% interval 41.0% – 70.7%
95% interval 48.4% – 77.3%
+7.7pp difference (treatment − control), p=0.49. Difference is not statistically significant at alpha=0.05.
At this baseline, detecting a 3pp change at 80% power needs roughly 4,250 participants per arm. Until an organizer runs that, the honest answer is “not proven” — and the product says so instead of shipping a claim.