A/B Testing
Compare variants with randomized controlled experiments.
Explanation
A/B testing is the gold standard for proving that changes actually cause improvements rather than just correlating with them. You randomly assign users to different versions of your product and measure the difference in outcomes. This controlled experimentation approach is used by every major tech company because even small improvements can compound into significant results over time.
Real-World Example
Google tested 41 shades of blue for links—extra $200M revenue. Amazon tests everything: one pixel change in button placement = $300M/year. Booking.com runs 1000+ tests simultaneously. Your test: Red vs Green button might seem trivial, but could mean 5% more conversions.
How to Apply
Define success metric first. Calculate sample size needed (online calculators). Run test to completion—don't peek. Check statistical significance. Watch for novelty effects. Test one thing at a time. Document everything: hypothesis, variants, results, learnings. Even failed tests teach something.