A/B Test Winner Detector
Automatically declare winners in your GA4 experiments
Nora monitors your GA4 experiments and alerts you when one variant has statistical significance — telling you which version to roll out sitewide.
A/B testing is powerful but requires statistical rigor. Too many tests fail because teams declare winners too early or with insufficient data. Nora continuously monitors all active GA4 experiments and checks whether any variant has achieved statistical significance (95% confidence that results aren't random). When an experiment reaches significance, Nora alerts you with: variant name, lift percentage, sample size, confidence level, and a recommendation to launch the winner. If a variant is losing badly, Nora flags it for early termination to save traffic waste. Nora also prevents false positives by accounting for multiple comparisons and adjusting confidence thresholds. For a high-traffic site running 5 concurrent experiments, this saves hours of manual monitoring and ensures you launch winners fast.
How it works
- Fetch all active GA4 experiments and their variant performance data
- Calculate conversion rate and confidence interval for each variant
- Check if any variant achieved 95%+ statistical significance
- Identify clear losers (performing 15%+ worse than control)
- Alert on statistically significant winners with lift and confidence level
- Recommend early termination of losing variants to preserve traffic
Frequently asked questions
What does "A/B Test Winner Detector" do?
Nora monitors your GA4 experiments and alerts you when one variant has statistical significance — telling you which version to roll out sitewide.
How long does setup take?
Under 5 minutes. Connect your tools and Nora handles the rest.
Which tools does this use?
Uses Google Analytics 4, run by your Marketing Manager.
How much time does this save?
Saves approximately 3 hours/week, running daily at 6:00 pm.