What problem does it solve? Teams often ship features without knowing whether they worked, or optimize the wrong metrics and end up with dark patterns and misleading dashboards. This Skill connects design decisions to observable evidence by defining what to measure, how to measure it, and how to act on what you learn. ## Core Features & Use Cases - Metric Selection with HEART and GSM: Applies Google's HEART framework (Happiness, Engagement, Adoption, Retention, Task success) and Goal-Signal-Metric mapping to pick the 2-3 dimensions that matter per feature, with counter-metrics for every optimized metric. - A/B Test and Funnel Design: Produces hypothesis structures, minimum detectable effect targets, sample size tables, guardrail metrics, and segmented funnel analyses paired with qualitative research. - Ethical Measurement Review: Detects Goodhart's Law risks and dark metric patterns, pairing every business metric with a user-outcome metric. - Use Case: After launching a new checkout flow, use this Skill to build a GSM chain, design a properly powered A/B test with guardrail metrics, and analyze the funnel drop-offs segmented by device and user type. ## Quick Start Ask the AI to define success metrics and an A/B test plan for your new feature using the measure skill.