COCOMO II parameters and IDPD: bilateral relevances

Abstract

The phenomenon called Incremental Development Productivity Decline (IDPD) is presumed to be present in all incremental soft-ware projects to some extent. COCOMO II is a popular parametric cost estimation model that has not yet been adapted to account for the challenges that IDPD poses to cost estimation. Instead, its cost driver and scale factors stay constant throughout the increments of a project. While a simple response could be to make these parameters variable per increment, questions are raised as to whether the existing parameters are enough to predict the behavior of an incrementally developed project even in that case. Individual COCOMO II parameters are evaluated with regard to their development over the course of increments and how they influence IDPD. The reverse is also done. In light of data collected in recent experimental projects, additional new variable parameters that either extend COCOMO II or could stand on their own are proposed.