A/B Testing Metrics: Choose the Primary Metric Closest to Profit

The best A/B testing metric is usually the measurable outcome closest to incremental contribution per eligible visitor, user, or account. This guide separates true decision metrics, operational primaries, leading indicators, guardrails, and diagnostics—then maps ecommerce, subscription, pricing, lead-generation, marketplace, and cost-changing experiments to the metrics that should actually determine the winner.

PostHog vs GA4: Analyst’s Guide

PostHog is usually better suited than the GA4 reporting interface to be the operational source of truth for growth decisions. It provides direct event-level investigation, explicit identity, flexible SQL, behavioral analysis, and experimentation in one environment. GA4 remains valuable for standardized acquisition and Google Ads reporting; when raw GA4 data is modeled in BigQuery, the warehouse becomes the real source of truth.

Experimentation System Audit: Can You Trust Your A/B Test Results?

An A/B result is only as trustworthy as the system that produced it. This audit framework examines eligibility, assignment, bucketing, identity persistence, exposure, sample-ratio mismatch, metric definitions, conversion windows, and statistical analysis. It also introduces the Zero Experiment: a production A/A calibration test designed to reveal whether the system creates lift where no treatment exists.