posthog/ai-plugin · Official

diagnosing-experiment-health

Runs diagnostics and a health check on one PostHog experiment: its setup, exposures, results and changes during the run. Covers 0 exposures, sample ratio mismatch, lost or uneven exposures, users in multiple variants, identity faults, who the experiment counts, significance traps (peeking, A/A, 'target reached', Bayesian vs Frequentist, sequential, CUPED), mid-run edits, pause and freeze, and survey follow-up. TRIGGER when: user asks 'is my experiment healthy / set up right / biased?' or 'why 0 exposures?', asks why it counts different people than their insight, mentions the bias or mismatch warning, an uneven split, significance that flips, numbers that disagree with their SQL, results that changed after an edit, or wants user feedback on an experiment. DO NOT TRIGGER when: creating an experiment (use creating-experiments), only configuring rollout (use configuring-experiment-rollout) or metrics (use configuring-experiment-analytics), or only asking lifecycle questions (use managing-experiment-lifecycle).