Heuristic Evaluation (Nielsen's 10 Principles)
Overview
Heuristic evaluation is an expert review method that assesses a user interface against established usability principles. It's fast (2-4 hours), cheap (no user recruitment), and finds 40-60% of usability issues. Use it as a complement to, not replacement for, user testing.
Framework
IRON LAW: Every Violation Gets a Severity Rating
Finding a violation is half the work. Rating its severity is the other half.
A cosmetic inconsistency and a critical workflow blocker are both "violations"
but require completely different response urgency.
0 = Not a usability problem
1 = Cosmetic only — fix if time permits
2 = Minor — low priority
3 = Major — important to fix, high priority
4 = Catastrophe — must fix before releaseNielsen's 10 Heuristics
| # | Heuristic | Question to Ask |
|---|---|---|
| 1 | Visibility of system status | Does the user always know what's happening? (loading indicators, progress bars, confirmations) |
| 2 | Match between system and real world | Does it use the user's language, not system jargon? Are conventions familiar? |
| 3 | User control and freedom | Can users undo, redo, go back, cancel? Is there an emergency exit? |
| 4 | Consistency and standards | Are the same actions/words used consistently? Does it follow platform conventions? |
| 5 | Error prevention | Does the design prevent errors before they happen? (confirmations, constraints, defaults) |
| 6 | Recognition rather than recall | Are options visible? Can users recognize rather than remember? |
| 7 | Flexibility and efficiency of use | Are there shortcuts for experts? Can users customize frequent actions? |
| 8 | Aesthetic and minimalist design | Is every element necessary? Does extra information compete with relevant info? |
| 9 | Help users recognize, diagnose, and recover from errors | Are error messages helpful? Do they explain what went wrong and how to fix it? |
| 10 | Help and documentation | Is help available? Is it searchable, task-oriented, and concise? |
Evaluation Process
- Define scope: Which screens/flows to evaluate
- Walk through the interface 2-3 times with different user tasks
- Flag violations: Note each violation with heuristic #, location, description
- Rate severity: 0-4 scale for each violation
- Prioritize: Fix severity 4 and 3 first
- Report: Organize findings by severity, not by heuristic number
Output Format
# Heuristic Evaluation: {Product/Feature}
## Summary
- Total violations found: {N}
- Severity 4 (catastrophe): {N}
- Severity 3 (major): {N}
- Severity 2 (minor): {N}
- Severity 1 (cosmetic): {N}
## Critical Issues (Severity 3-4)
| # | Location | Heuristic | Issue | Severity | Recommendation |
|---|----------|-----------|-------|----------|---------------|
| 1 | {screen/element} | {#N: name} | {description} | 3/4 | {fix} |
## Other Issues (Severity 1-2)
| # | Location | Heuristic | Issue | Severity |
|---|----------|-----------|-------|----------|
| ... | ... | ... | ... | ... |Examples
Correct Application
Scenario: Evaluating a food delivery app checkout flow
| Location | Heuristic | Issue | Severity |
|---|---|---|---|
| Cart page | #1 Visibility | No loading indicator when adding items — user taps multiple times | 3 |
| Payment | #5 Error prevention | No confirmation before placing order — accidental orders happen | 4 |
| Error screen | #9 Error recovery | "Error 500" with no explanation or retry button | 4 |
| Address form | #6 Recognition | User must type full address instead of selecting from saved addresses | 2 |
Priority: Fix #5 and #9 immediately (severity 4) ✓
Incorrect Application
- "The app looks ugly" → Not a heuristic violation. "Aesthetic and minimalist design" (#8) is about information hierarchy, not visual attractiveness. A specific violation would be: "Product page shows 15 data fields simultaneously, burying the price and 'Add to Cart' button."
Gotchas
- 3-5 evaluators find 75% of issues: One evaluator finds ~35%. Diminishing returns after 5. If possible, have multiple evaluators work independently then merge findings.
- Heuristic evaluation finds problems, not solutions: It tells you what's wrong, not how to fix it. Solution design is a separate step.
- Not a substitute for user testing: Experts predict user behavior imperfectly. Some "violations" that experts flag don't bother real users, and some real problems experts miss.
- Mobile vs desktop: Apply heuristics separately for each platform. Touch targets, screen real estate, and interaction patterns differ significantly.
- Accessibility is not a heuristic: Nielsen's 10 don't explicitly cover accessibility (color contrast, screen reader support, keyboard navigation). Add WCAG checks separately.
References
- For WCAG accessibility checklist, see
references/wcag-checklist.md