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Monday, January 17, 2011

The COCOMO II (Constructive Cost Estimation Model) Model

COCOMO II is an extension to the COCOMO model. COCOMO II takes into account new development processes, increased flexibility in software development, need for decision making with incomplete information and new data about projects.

COCOMO II is really three different models :
- The Application Composition Model used for prototyping.
- The Early Design Model used when requirements are available but design has not yet started.
- The Post-Architecture Model used once the system architecture has been designed.

COCOMO II models require sizing information. Three different sizing options are available as part of the model hierarchy i.e. object points, function points, and lines of source codes.
The application composition model uses object points which is an indirect software measure that is computed using counts of the number of screens, reports and components likely to be required to build the application.

DIFFERENCES BETWEEN COCOMO I AND COCOMO II


- COCOMO I requires software size in KDSI as an input, but COCOMO II is based on KSLOC.
- COCOMO I provides point estimates of effort and schedule, but COCOMO II provides likely ranges of estimates.
- In COCOMO II, the estimation equation exponent is determined by five scale factors instead of three.
- Data points in COCOMO I: 63 and COCOMO II: 161.
- COCOMO II adjusts for software reuse and re-engineering but COCOMO I made little accommodation for these factors.


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