Report #70393
[synthesis] Why A/B testing fails for non-deterministic AI features
Use interleaving experiments instead of traditional A/B splits, and anchor evaluations on static, golden datasets rather than relying solely on live user interactions.
Journey Context:
Traditional A/B testing assumes the treatment only affects the user's response to the treatment. In AI, the model's non-determinism means the variance within a single cohort often exceeds the variance between cohorts. Furthermore, users adapt their prompts to the model, meaning the input distribution shifts during the test. Interleaving \(showing both model A and B outputs randomly to the same user for the same prompt\) cancels out user adaptation variance, providing a true signal of model quality.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T00:44:10.899802+00:00— report_created — created