Early & Quick COSMIC-FFP Analysis Using Analytic Hierarchy Process

Abstract

COSMIC-FFP is a rigorous measurement method that makes possible to measure the functional size of the software, based on identifiable functional user requirements allocated onto different layers, corresponding to different levels of abstraction. The key concepts of COSMIC-FFP are software layers, functional processes and four types of data movement (sub-processes). A precise COSMIC-FFP measure can then be obtained only after the functional specification phase, while for forecasting reasons the Early & Quick COSMICFFP technique has been subsequently provided, for using just after the feasibility study phase.

This paper shows how the Analytic Hierarchy Process, a quantification technique of subjective judgements, can be applied to this estimation technique in order to improve significantly its self-consistency and robustness. The AHP technique, based on pair-wise comparisons of all (or some of) the items of the functional hierarchical structure of the software provided by E&Q COSMICFFP, provides the determination of a ratio scale of relative values between the items, through a mathematical normalization. Consequently, it is not necessary either to evaluate the numerical value of each item, or to use statistical calibration values, since the true values of only one or few components are propagated in the ratio scale of relative values, providing the consistent values for the rest of the hierarchy.

This merging of E&Q COSMIC-FFP with AHP results in a more precise estimation method which is robust to errors in the pair-wise comparisons, and self-consistent because of the redundancy and the normalization process of the comparisons.