Software Metrics
A
software metric is a measure of software characteristics which are measurable
or countable. Software metrics are valuable for many reasons, including
measuring software performance, planning work items, measuring productivity,
and many other uses.
Within
the software development process, many metrics are that are all connected.
Software metrics are similar to the four functions of management: Planning,
Organization, Control, or Improvement.
Classification of
Software Metrics
Software metrics can be classified into two types as follows:
1. Product Metrics: These are the measures of various
characteristics of the software product. The two important software
characteristics are:
- Size
and complexity of software.
- Quality
and reliability of software.
These
metrics can be computed for different stages of SDLC.
2. Process Metrics: These are the measures of various characteristics of the software development process. For example, the efficiency of fault detection. They are used to measure the characteristics of methods, techniques, and tools that are used for developing software.
Types
of Metrics
Internal metrics: Internal metrics are the metrics used for measuring
properties that are viewed to be of greater importance to a software developer.
For example, Lines of Code (LOC) measure.
External metrics: External metrics are the metrics used for measuring
properties that are viewed to be of greater importance to the user, e.g.,
portability, reliability, functionality, usability, etc.
Hybrid metrics: Hybrid metrics are the metrics that combine product,
process, and resource metrics. For example, cost per FP where FP stands for
Function Point Metric.
Project metrics: Project metrics are the metrics used by the project
manager to check the project's progress. Data from the past projects are used
to collect various metrics, like time and cost; these estimates are used as a
base of new software. Note that as the project proceeds, the project manager
will check its progress from time-to-time and will compare the effort, cost,
and time with the original effort, cost and time. Also understand that these
metrics are used to decrease the development costs, time efforts and risks. The
project quality can also be improved. As quality improves, the number of errors
and time, as well as cost required, is also reduced.
Advantage of
Software Metrics
Comparative
study of various design methodology of software systems.
For
analysis, comparison, and critical study of different programming language
concerning their characteristics.
In comparing and evaluating the capabilities and productivity of people
involved in software development.
In the preparation of software quality specifications.
In
the verification of compliance of software systems requirements and
specifications.
In
making inference about the effort to be put in the design and development of
the software systems.
In
getting an idea about the complexity of the code.
In
taking decisions regarding further division of a complex module is to be done
or not.
In
guiding resource manager for their proper utilization.
In
comparison and making design tradeoffs between software development and
maintenance cost.
In providing feedback to software managers about the progress and quality
during various phases of the software development life cycle.
In
the allocation of testing resources for testing the code.
Disadvantage of
Software Metrics
The
application of software metrics is not always easy, and in some cases, it is
difficult and costly.
The
verification and justification of software metrics are based on
historical/empirical data whose validity is difficult to verify.
These
are useful for managing software products but not for evaluating the
performance of the technical staff.
The definition and derivation of Software metrics are usually based on assuming
which are not standardized and may depend upon tools available and working
environment.
Most
of the predictive models rely on estimates of certain variables which are often
not known precisely.