Software project development cost estimation

This paper reports the results of an empirical investigation of the relationships between effort expended, time scales, and project size for software project development. The observed relationships were compared with those predicted by Lawrence Putnam's Rayleigh curve model and Barry Boehm's COCOMO model. The results suggested that although the form of the basic empirical relationships were consistent with the cost models, the COCOMO model was a poor estimator of cost for the current data set and the data did not follow the Rayleigh curve suggested by Putnam. However, the results did suggest that it was possible to develop cost models tailored to a particular environment and to improve the precision of the models as they are used during the development cycle by including additional information such as the known effort for the early development phases. The paper finishes by discussing some of the problems involved in developing useful cost models.