Flags can assign users deterministically to variants without code redeploys.
Design the Experiment
- Define hypothesis
- Power analysis
- Primary metric
Run & Analyze
- Guard against SRM
- Track exposure
- Use sequential testing carefully
Measuring Uplift
- Choose attribution window
- Segment by new vs. returning
- Beware novelty effects
Common Pitfalls
- SRM due to targeting rules
- Peeking and p‑hacking
- Undersized samples
Case Study: Signup Flow Variant
Variant B removed a field and improved conversion by 4.3% at 95% confidence. Exposure logs confirmed no SRM; rollout completed in 2 days.
FAQ
- How long to run tests? Until you reach required sample size with stable traffic.
- What if SRM is detected? Pause, investigate targeting/evaluation bugs, then restart.
Conclusion
Multivariate flags plus good discipline produce trustworthy experiments that guide product decisions.