These correlation functions serve here as means for computing the relationship between an actual software system and the required system. Software systems and software projects are unique. Models of software quality or productivity therefore have to be product or project specific. The modeling technique proposed uses weight functions to define factors of quality or productivity in terms of evaluation factors. As a result one obtains an acyclic decomposition graph.
Software quality is defined by a hierarchy of factors of software quality.
The relations between the factors can be defined according to specific requirements. An overall system quality can be computed by comparing quality values each hierarch level. Quality or productivity then is to be defined as the distance of the actual graph and a required graph. An assessment technique is proposed which enables decompositions of any reasonable depth. It is shown how specific models are to be generated by a set of elementary production rules.