Traceability Matrix (Requirements Traceability Matrix, RTM)
A traceability matrix — in the requirements context usually a Requirements Traceability Matrix (RTM) — is a table that maps relationships between development artifacts and thereby establishes bidirectional requirements traceability in the project. One artifact type is placed on one axis (e.g. requirements), another on the other axis (e.g. validations); a mark in the cell means: these two artifacts are linked.
A step-by-step guide with examples is provided in our article How to Create a Requirements Traceability Matrix.
How does an RTM work?
The matrix does not contain the artifacts themselves, but references them via unique IDs. Precisely this simplicity is its strength: an RTM can be maintained in Excel or even drawn on a whiteboard. It can be read in both directions:
- Forward traceability: Which requirements are not properly validated?
- Backward traceability: Which test cases do not validate any requirement?
Creating one follows three mandatory steps: identify the artifact types, define the relationships between the artifacts, and create a separate matrix for each link type. Optionally, cumulative views across entire trace chains can be derived from this — for example the share of customer requirements covered by a test (see Requirements Coverage).
What are the limits?
The RTM can make gaps visible very efficiently, but cannot explain why a problem exists. Above all, it scales poorly: with several V-model levels and thousands of rows and columns, a manually maintained matrix quickly becomes unmaintainable. For complex, regulated projects, the transition to a versioned traceability graph with tool support has therefore proven itself — read more on our page Requirements Traceability.