Effects of Software Process Maturity on COCOMO II's Effort Estimation from CMMI Perspective

摘要

The software cost estimation model, COnstructive COst MOdel (COCOMO), in its last update (COCOMO II) has a set of seventeen cost drivers as well as a set of five scale factors. Process Maturity, PMAT, is one of that five scale factors and its ratings are based on the Software Capability Maturity Model, SW-CMM, which is used to evaluate an organization's process maturity. In this paper, an investigation into the effect of process maturity on software development effort is presented by deriving the new set of COCOMO II's PMAT rating values based on the most recent version of SW-CMM, i.e. Capability Maturity Model Integration (CMMI). COCOMO II's data collection questionnaire was prepared and distributed to a group of selected software development organizations. The precise data for the analysis was collected from the record of 30 completed projects which spanned the range of CMMI Levels, from Level 1 (Level 1 Lower half and Level 1 Upper half) to Level 4, where 6 data points were collected from each level. The Ideal Scale Factor (ISF) method was used in order to withhold the effect of the COCOMO II's PMAT scale factor. All prediction accuracies were measured using PRED (30). The study shows that our proposed model (with the new PMAT rating values) yields better estimates comparing with the Generic COCOMO II model's estimates.