Page 32 - DCAP304_DCAP515_SOFTWARE_PROJECT_MANAGEMENT

Software Project Management

Notes inputs and outputs, user interactions, external interfaces and files used by the system. The
function points are then converted to number of lines of source code using the tables
provided by the COCOMO model.

Application Area

COCOMO is a well-known experiential algorithmic cost estimation procedure. It is well-
documented, in the public domain and is supported by public domain and commercial tools.
It has been extensively used and has a long pedigree from its first instantiation in 1981. The
application of the first instantiation of the model was limited due to the quite large constraints
on the development process. This issue has been mitigated by continued improvements on, and
extensions of the model, resulting in COCOMO 2. A refinement of the model for the Ada
programming language is available as well.
Advantages

 Though it’s hard to pinpoint the exact cost of any given project, one can still obtain usable
data by calculating optimistic and pessimistic estimates.

 Implementation and execution of the model is very easy and proficient. As a result, it is
supported by public as well as commercial tools.
 COCOMO is a well-known and well-documented method.

Disadvantages

 It is quite difficult to come up with acceptable estimates for the size of a project when the
latter still in an early stage of development.
 The use of the number of lines of source code as a measure of difficulty is highly disputable.
Even though COCOMO tries to take this into account by providing different tables for all
major programming languages, there are still lots of discrepancy such as: expressivity
differences between programmers, usage of subroutines, general code reuse, and etcetera.

 Some input parameters in the model cannot by determined quantitatively; they need be
estimated as well. A few examples: experience and productivity of the programmers,
maturity and capability of CASE tools. The accuracy of the ultimate estimates of the
COCOMO model depends considerably on the exactness of the initial ones.
 The COCOMO model has not been revised since 1995. Consequently, it is likely the model
fails to take into account new theories and practices in the Software Engineering field,
resulting in worse estimates.

Usage in Methodologies

As confirmed above, the COCOMO model can only be applied when the project in question
satisfies a given number of criteria. Moreover, it is advisable to try out other estimation techniques,
as to get a feeling of the accuracy of the estimates that have been obtained. Other probable
techniques include:
 Expert judgment
 Estimation by analogy

 Other algorithmic cost estimation models

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