Optimizing email open and conversion rates requires disciplined hypothesis testing. Declaring winning subject lines without statistical significance leads to false positives and degraded campaign performance.
1. Split-Test Sample Size Formula
📐 Sample Size Calculation Formula
N = [ 2 * (Z_alpha/2 + Z_beta)^2 * p * (1 - p) ] / (delta)^2
# Requires 95% Confidence (p < 0.05) and 80% Power (beta = 0.20) before winner selection