Traceability Matrix

Reference Files

• references/traceability-template.md - Template table for the RTM with all standard columns plus a V-Model diagram showing the requirement-to-test level mapping. Read this in Step 2 when setting up the matrix structure.

Overview

Based on Requirements Engineering by Elizabeth Hull, Ken Jackson, and Jeremy Dick - the most thorough treatment of pre-RS traceability (source to requirement) and post-RS traceability (requirement to design to test to delivery). Also draws on the BABOK Guide v3 (IIBA) Requirements Life Cycle Management knowledge area, and Mastering the Requirements Process by Robertson & Robertson where each Volere Snow Card links requirement to event, source, and rationale. The key insight from Hull: traceability is not a bureaucratic checkbox. It answers three critical questions: "Why does this requirement exist?" (backward), "Is this requirement implemented?" (forward), and "Is anything implemented that wasn't required?" (coverage).

Workflow

Step 1: Define the traceability scope

PROJECT: [name]
TRACEABILITY DIRECTION:
  - Backward (pre-RS): Source -> Business Req -> Stakeholder Req -> Functional Req
  - Forward (post-RS): Functional Req -> Design -> Code -> Test Case -> Test Result
DEPTH: [How many levels of tracing? Minimum: requirement -> test case]
TOOL: [spreadsheet, requirements management tool, or issue tracker]

Step 2: Set up the matrix structure

Use the template from references/traceability-template.md. The V-Model determines which requirement level maps to which test level:

Business Requirements  <------>  Acceptance Tests (UAT)
  Stakeholder Requirements  <------>  System Tests
    Functional Requirements  <------>  Integration Tests
      Component/Technical Specs  <------>  Unit Tests

Step 3: Populate backward traceability (source to requirement)

For each requirement, trace backward:

| Req ID | Source | Business Req | Stakeholder Req | Notes |
|--------|--------|-------------|-----------------|-------|
| FR-AUTH-001 | ISO 27001, Security team | BO-3: Reduce security incidents | SR-12: Lock after failed attempts | |
| FR-ORD-005 | Customer feedback Q3 | BO-1: Improve order experience | SR-04: Real-time order tracking | |

This answers: "Why does this requirement exist?" and "What happens if we remove it?"

Step 4: Populate forward traceability (requirement to delivery)

For each requirement, trace forward:

| Req ID | Design Ref | Test Case ID | Test Result | Status |
|--------|-----------|-------------|-------------|--------|
| FR-AUTH-001 | DD-Auth-3.2 | TC-AUTH-001, TC-AUTH-002 | Pass | Verified |
| FR-ORD-005 | DD-Ord-5.1 | TC-ORD-012 | Fail (defect #234) | Open |

This answers: "Is this requirement implemented and tested?"

Step 5: Analyze coverage gaps

Run three coverage checks:

Forward coverage: % of requirements with at least one test case

Forward coverage = (Requirements with test cases / Total requirements) x 100%
Target: 100% for Must requirements, 90%+ for Should requirements

Backward coverage: % of requirements traceable to a business source

Backward coverage = (Requirements with source / Total requirements) x 100%
Target: 100% - any requirement without a source is suspect

Gold plating check: Test cases or design elements that don't trace to any requirement

Orphan tests = Test cases with no linked requirement
Orphan design = Design components with no linked requirement

These indicate scope creep or unnecessary work.

Step 6: Track requirement states

Monitor each requirement through its lifecycle:

| State | Definition |
|-------|-----------|
| Proposed | Identified but not yet approved |
| Approved | Accepted for implementation |
| Designed | Design artifact created |
| Implemented | Code complete |
| Tested | Test cases executed |
| Verified | All tests pass, accepted |
| Deferred | Postponed to a future release |

Step 7: Output and maintain the RTM

Deliver the traceability matrix with coverage metrics. Update it as requirements change - the matrix is a living document, not a one-time artifact.

Anti-Patterns

1. Traceability as a checkbox exercise Bad: Filling in the matrix after everything is built, just to satisfy an audit. Good: Building the matrix as requirements are written and maintaining it through delivery.

2. Forward-only traceability Bad: Linking requirements to tests but not back to business sources. Good: Both directions - backward (why) and forward (is it done).

3. No coverage analysis Bad: A complete-looking matrix that's never analyzed for gaps. Good: Run coverage metrics regularly - forward, backward, and gold plating checks.

4. One-to-one assumption Bad: Expecting every requirement maps to exactly one test. Good: Many-to-many is normal - one requirement may need multiple tests; one test may verify multiple requirements.

5. Stale matrix Bad: Matrix created in month 1, never updated when requirements changed. Good: Update the matrix whenever a requirement is added, changed, deferred, or removed.

Quality Checklist

• Traceability direction defined (backward and forward)
• V-Model mapping established (requirement level to test level)
• Every requirement has backward traceability to a source
• Every Must requirement has forward traceability to at least one test case
• Forward coverage calculated and meets target (100% for Must)
• Backward coverage calculated (100% target)
• Gold plating check done (orphan tests and design elements identified)
• Requirement states tracked through lifecycle
• Matrix is maintained as a living document, not a snapshot