Bidirectional Influence of Defects and Functional Size

This paper reports on a research project investigating the contribution of functional size measurers to finding defects in requirements. In previous experiments, the concurrent inspection of the same requirements document by a measurer in addition to inspectors showed that the functional size measurement activity adds value in finding functional defects that inspectors have not identified. This paper presents an analysis of the influence of defects on the functional size once many of the identified defects have been fixed. For these experiments, the measurers used COSMIC - ISO 19761 to measure functional size and to find defects. Experiments findings show an increase in functional size and a decrease in defects identified.