Achieving Excellence in Software Development Using Metrics ◾ 97
When use cases are known, by assigning different weight factors to different
actor types, we can calculate use case point. is metric can be set up early in the
project and used as an estimator of cost and time. Technical and environmental
factors can be incorporated to enrich the use case point for estimation.
Similarly, when test cases are developed, a metric called test case point (TCP)
can be developed by assigning complexity weights to the test cases. e sum of
TCP can be used to estimate effort and schedule.
Alternatively, we can measure object points based on screens and reports in the
software.
Use case points, test case points, and object points are variants of functional
size. ey can be converted into FP by using appropriate scale factors.
Measure functional size as the project starts.
is will bring clarity into requirements and help in the estimation of cost,
schedule and quality.
Once functional size is measured, the information is used to estimate man-
power and time required to execute the project. is is conveniently performed by
applying any regression model that correlates size with effort. COCOMO is one
such model, or one can use homegrown models for this purpose.
ere is a simpler way to estimate effort. We can identify the type of soft-
ware we have to develop. Yong Xia identifies five software types: end-user software
(developed for the personal use of the developer), management information system,
outsourced projects, system software, commercial software, and military software.
On the basis of type, we can anticipate the FP per staff month, which can vary from
1000 to 35 [9]. Using this conversion factor, we can quickly arrive at the effort esti-
mate. Once effort is known, we can derive time required, again by using available
regression relationships.
Early metrics capture functional size and arrive at effort estimates; measure-
ment and estimation are harmoniously blended.
Project Progress Using Earned Value Metrics
Tracking Progress
Whether one builds software or a skyscraper, earned value metrics can be used to
advantage. To constrict earned value metric, we need to make two basic observa-
tions: schedule and cost are measured at every milestone.
e first achievement of EVM is in the way it distinguishes value from cost.
Project earns value by doing work. Value is measured as follows:
Budgeted cost of work is its value.