Project effort estimation (COCOMO I)
The summarized steps of the COCOMO are as follows
pick an estimate of what is considered as three possible project
modes:
organic (simple)
semidetached (intermediate)
embedded (difficult)
estimate the size of the project in KLOC (COCOMO II allowed
other metrics such as function point)
review 15 factors, known as cost drivers, and estimate the
amount of impact each factor will have on project
determine the effort for the software project by inserting the
estimated values into the effort formula for the chosen mode
Project effort estimation (COCOMO I)
The mode of the project is chosen based on the following
eight parameters
the team’s understanding of the project objectives
the team’s experience with similar or related projects
the project’s need to conform with established requirements
the project’s need to conform with established external interfaces
the need to develop the project concurrently with new systems
and new operational procedures
the project’s need for new and innovative technology,
architecture, or other constraints
the project’s need to meet or beat the schedule
project size
Project effort estimation (COCOMO I)
The first step of choosing the mode is non-trivial task
because no software project falls neatly into a single
category
The three modes of organic, semidetached, and
embedded may be roughly equated to simple,
intermediate, and difficult projects, respectively
Most of projects will have a mix of project characteristics
Project effort estimation (COCOMO I)
Once the project mode is determined, an estimation
formula needs to be chosen
The following are the corresponding estimation formulas
for the three modes, with the effort unit indicated in
person-months
organic: effort = [3.2 X (size)1.05] X PROD (f’ s)
semidetached: effort = [3.0 X (size)1.12] X PROD (f’ s)
embedded: effort = [2.0 X (size)1.20] X PROD (f’ s)