Pitfalls of A/B Testing

“The outside world often has a much larger effect on metrics than product changes do.” —Jan Overgoor [related holidays, weather, payday, time of day, major news]

The best roundup I found is via Shopify and via Optimizely. And Neil Patel’s piece on Netflix is v useful. For a tragic example of testing gone bad, this PNAS paper says it all. —JM