The objective of this paper is to examine the gaps and overlaps between software and systems engineering cost models with intent to harmonize the estimates in engineering engineering estimation. In particular, we evaluate the central assumptions of the COSYSMO and COCOMO II models and propose an approach to identify gaps and overlaps between them. We provide guidelines on how to reconcile and resolve the identified gaps and overlaps. The ultimate purpose of this work is to develop effective techniques for accurately estimating the combined systems and software engineering effort for software-intensive systems
