A quality model for the systematic assessment of requirements traceability

Traceability is an important quality of software requirements and allows to describe and follow their life throughout a development project. The importance of traceable requirements is reflected by the fact that requirements standards, safety regulations, and maturity models explicitly demand for it. In practice, traceability is created and maintained by humans, which make mistakes. In result, existing traces are potentially of dubious quality but serve as the foundation for high impact development decisions. We found in previous studies that practitioners miss clear guidance on how to systematically assess the quality of existing traces. In this paper, we review the elements involved in establishing traceability in a development project and derive a quality model that specifies per element the acceptable state (Traceability Gate) and unacceptable deviations (Traceability Problem) from this state. We describe and formally define how both, the acceptable states and the unacceptable deviations can be detected in order to enable practitioners to systematically assess their project´s traceability. We evaluated the proposed model through an expert survey. The participating experts considered the quality model to be complete and attested that its quality criteria are of high relevance. We further found that the experts weight the occurrence of different traceability problems with different criticality. This information can be used to quantify the impact of traceability problems and to prioritize the assessment of traceability elements.