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 release

Nielsen'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

1. Define scope: Which screens/flows to evaluate
2. Walk through the interface 2-3 times with different user tasks
3. Flag violations: Note each violation with heuristic #, location, description
4. Rate severity: 0-4 scale for each violation
5. Prioritize: Fix severity 4 and 3 first
6. Report: Organize findings by severity, not by heuristic number

Output Format

markdown
# 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