Design experiments that actually prove something. Most A/B tests fail because they test vague ideas, run too short, or peek at results. A well-designed experiment has a clear hypothesis, adequate power, and a pre-committed analysis plan.
Every experiment starts with a written hypothesis before any work begins:
"If we [make this specific change] for [this audience], then [this metric] will [change in this direction] by [this amount], because [this reason based on evidence]."
Design hypothesis-driven experiments and A/B tests with proper methodology. Use when asked to design an A/B test, validate a hypothesis, plan an experiment, or set up a test for a product change. Covers hypothesis writing, sample size, and common mistakes. Source: assimovt/productskills.