Software Function, Source Lines of Code, and Development Effort Prediction: A Software Science Validation

TLDR

Predicting software size and development effort is a key challenge, and an alternative approach is to estimate the software’s functional size using Albrecht’s function point methodology based on data input, output, master files, and inquiries. This study aims to demonstrate the equivalence between Albrecht’s function point metric and Halstead’s software science models, including the soft‑content variant. Function points are quantified as a weighted sum of the numbers of inputs, outputs, master files, and inquiries provided to or generated by the software. The results confirm that Albrecht’s function points are equivalent to Halstead’s software science and soft‑content models, validating the function‑point approach.

Abstract

One of the most important problems faced by software developers and users is the prediction of the size of a programming system and its development effort. As an alternative to "size," one might deal with a measure of the "function" that the software is to perform. Albrecht [1] has developed a methodology to estimate the amount of the "function" the software is to perform, in terms of the data it is to use (absorb) and to generate (produce). The "function" is quantified as "function points," essentially, a weighted sum of the numbers of "inputs," "outputs,"master files," and "inquiries" provided to, or generated by, the software. This paper demonstrates the equivalence between Albrecht's external input/output data flow representative of a program (the "function points" metric) and Halstead's [2] "software science" or "software linguistics" model of a program as well as the "soft content" variation of Halstead's model suggested by Gaffney [7].