The COnstructive COst MOdel II (COCOMO® II) is a software cost, effort, and schedule model. COCOMO® II is the latest major extension to the original COCOMO® (also known as COCOMO® 81) model published in 1981. It consists of three submodels, each one offering increased accuracy the further along one is in the project planning and design process. Listed in increasing input parameters and accuracy, these submodels are called the Applications Composition, Early Design, and Post-architecture models.

COCOMO® II can be used for the following major decision situations:

  • Making investment or other financial decisions involving a software development effort
  • Setting project budgets and schedules as a basis for planning and control
  • Deciding on or negotiating trade-offs among software cost, schedule, functionality, performance or quality factors
  • Making software cost and schedule risk management decisions
  • Deciding which parts of a software system to develop, reuse, lease, or purchase
  • Making legacy software inventory decisions: what parts to modify, phase out, outsource, etc.
  • Setting mixed investment strategies to improve organization’s software capability, via reuse, tools, process maturity, outsourcing, etc.
  • Deciding how to implement a process improvement strategy, such as that provided in the SEI CMMI

The original COCOMO® model was first published by Dr. Barry Boehm in 1981, and reflected the software development practices of the day. In the ensuing decade and a half, software development techniques changed dramatically. These changes included a move away from mainframe overnight batch processing to desktop-based real-time turnaround; a greatly increased emphasis on reusing existing software and building new systems using off-the-shelf software components; and spending as much effort to design and manage the software development process as was once spent creating the software product.

These changes and others began to make applying the original COCOMO® model problematic. The solution to the problem was to reinvent the model for the 1990s. After several years and the combined efforts of USC-CSSE, ISR at UC Irvine, and the COCOMO® II Project Affiliate Organizations, the result is COCOMO® II, a revised cost estimation model reflecting the changes in professional software development practice that have come about since the 1970s.

Details of the COCOMO® II model, such as the input parameter definitions, the model form, and how the model was calibrated, can be found in the book Software Cost Estimation with COCOMO II.