COCOMO Model in software engineering[check here]

COCOMO(COnstructive COst MOdel) cost and schedule estimation model was originally published in (Boehm 1981).COCOMO method is named after a popular beach boys song.
It became one of the most popular parametric cost estimation models of the 1980s. But COCOMO’ 81 along with its 1987 Ada update experienced difficulties in estimating the costs of software developed to new life-cycle processes and capabilities.

The COCOMO II research effort was started in 1994 at USC to address the issues on non-sequential and rapid development process models, re-engineering , reuse driven
approaches, object oriented approaches etc(USC-CSE 1997).
COCOMO II was initially published by Boehm et al. in the annals of software Engineering in 1995.The model has three sub-models:

• Applications composition Model
• Early Design Model
• Post-Architecture Model

These can be combined in various ways to deal with the current and likely software practices marketplace.

Application Composition Model

• The application composition model is used to estimate effort and schedule on projects that use integrated computer aided software engineering(I-CASE) tools for rapid application development.
• These projects are too diversified but sufficiently simple to be rapidly composed from interoperable components.
• Typical components are GUI builders, database or objects managers , middleware,for distributed processing or transaction processing etc. and domain-specific components such as financial, medical or industrial process control packages.
• The Applications Composition model is based on Object points (Banker et al. 1993).
• Object points are a count of the screens, reports and 3 GL language modules developed in the application.
• Each count is weighted by a three-level;simple, medium, difficult; complexity factor.
• This estimating approach is commensurate with the level of information available during the planning stages of application composition projects.

Early Design Model

• The Early Design Model involves the exploration of alternative system architectures and concepts of operation.
• This model is based on function points (or lines of code when available) and a set of five scale factors and 7 effort multipliers.

Post-Architecture Model

• The Post-Architecture model is used when top-level design is complete and detailed information about the project is available and as the name suggests, the software architecture is well defined and established.
• It estimates for the entire development lifecycle and is a detailed extension of the early-design model. This model is the closest in structure and formulation to the Intermediate COCOMO’ 81 and Ada COCOMO models.
• It uses source lines of code and/or function points for the sizing parameter, adjusted for reuse and breakage; a set of 17 effort multipliers and a set of 5 scale factors that determine the economies/dis-economies of scale of the software under development.The 5 scale factors replace the development modes in the COCOMO’ 81 model and refine the exponent in the Ada COCOMO model.
• The Post-Architecture Model has been calibrated to a database of 161 projects collected from commercial, aerospace, Government and non-profit organizations using the Bayesian approach by Chulani et al. in 1998 (Chulani et al. 1998b; Chulani 1998;Al Clark et al. 1998) and is discussed further in “Composite Techniques”.

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Originally published at https://www.csmates.com.