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Basic COCOMO
From www.jsc.nasa.gov/bu2/
This model is obsolete and should only be used for demonstration purposes.
This is a simple on-line cost model for estimating the number of person-months required to develop software.
The model also estimates the development schedule in months and produces an effort and schedule distribution by
major phases. This model is based on http://sunset.usc.edu/Research_Group/barry.htmlBarry
Boehm's Constructive Cost Model (COCOMO). This is the top-level model, Basic COCOMO, which is applicable to
the large majority of software projects.
Here is what Boehm says about the model: "Basic
COCOMO is good for rough order of magnitude estimates of software costs, but its accuracy is necessarily limited
because of its lack of factors to account for differences in hardware constraints, personnel quality and experience,
use of modern tools and techniques, and other project attributes known to have a significant influence on costs."
For more detailed information about COCOMO and software cost estimating in general, I strongly
recommend reading Software Engineering Economics (1981), by Barry
Boehm.
A number of additional COCOMO resources are available on the web.
The model estimates cost using one of three different development modes: organic, semidetached and embedded.
Here is a summary of how Boehm describes the modes:
- Organic
- In the organic mode, relatively small software teams develop software in a highly familiar, in-house environment.
Most people connected with the project have extensive experience in working with related systems within the organization,
and have a thorough understanding of how the system under development will contribute to the organizations objectives.
Very few organic-mode projects have developed products with more than 50 thousand delivered source instructions
(KDSI).
- Semidetached
- The semidetached mode of software development represents an intermediate stage between the organic and embedded
modes. "Intermediate" may mean either of two things:
- An intermediate level of project characteristic.
- A mixture of the organic and embedded mode characteristics.
The size range of a semidetached mode product generally extends up to 300 KDSI.
- Embedded
- The major distinguishing factor of an embedded-mode software project is a need to operate within tight constraints.
The product must operate within (is embedded in) a strongly coupled complex of hardware, software, regulations,
and operational procedures, such as an electronic funds transfer system or an air traffic control system.
Note. These models are provided as educational examples of technology developed and
used by cost engineers. Use at your own risk. These tools are written in JavaScript and require a browser with
JavaScript capability.
* The plans and requirements phase is calculated in addition to the nominal COCOMO estimate for effort and schedule.
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