What to Measure
Usability Metrics
| Metric | How | Good Signal |
|---|---|---|
| Task completion rate | Analytics, testing | >90% |
| Time on task | Session recordings | Decreasing over time |
| Error rate | Form analytics | <5% per field |
| Learnability | First-use vs repeated-use comparison | Converges quickly |
Business Metrics Designers Influence
| Metric | Design Lever |
|---|---|
| Conversion rate | Onboarding, CTA design, friction reduction |
| Retention | Feature discovery, habit formation, value delivery |
| NPS/CSAT | Overall experience quality |
| Support tickets | Error prevention, clarity, self-service |
| Revenue per user | Upgrade flow, pricing presentation |
Design System Metrics
- Component adoption rate
- Custom override frequency
- Time to build new features using system
- Design consistency score (visual audit)
Anti-Metrics
- Time on page (more isn't always better)
- Page views (bouncing between pages isn't engagement)
- Feature count (more features isn't more value)
- Design system component count (more components isn't healthier)