A traceability matrix is a documented report from the requirements database or repository. It contains all information requirements which determine the associated information to be stored with the requirements. We can use requirements management tools to capture associated information and add it to traceability matrix.
The below figure shows an example of forward and backward tracing between user and functional requirements:-
It can be seen in the above example that user and functional requirements are assigned with unique identifiers(IDs), user requirement identifiers begin with 'U' while functional requirement identifiers begin with 'S'. Tracing functional requirement S12 to its source i.e, user requirement U2 makes it clear that the requirement is erroneous because S12 states that the system shall calculate point to point travel time, which is not matching with the user requirement ID U2. Therefore, functional requirement with unique ID S12 must be eliminated, rewritten or corrected to build a correct traceability matrix.
Incomplete or irrelevant requirements eventually lead to poor traceability matrix design, which in turn increases customer dissatisfaction. Therefore only relevant and complete requirements must be included in a traceability matrix in order to make it effective.
The requirements which need to be included in traceability matrices should be determined at the start of the project and documented in the requirements management plan.