The Comparison and Improvement of Effort Estimates from Three Software Cost Models

This paper presents an empirical investigation of effort estimation techniques using three software cost models: Boehm's basic COCOMO model, Thebaut's COPMO model, and Putnam's model. The results, based on proprietary historical project data provided by a major computer manufacturer, are in three parts: (1) a comparison of the three mdels showing that more accurate estimates are obtained from the COPMO model; (2) improvements in the COPMO estimates by means of two techniques termed "submodeling" and "constructive modeling"; and (3) the definition and evaluation of a promising new technique, termed "adjustment multipliers", for improving a model's estimates. Finally, a second set of industrial data is used to confirm the general applicability of these improvement techniques.