What Are Software Metrics?

Software metrics are an integral part of the state-of- the-practice in software engineering.  More and more customers are specifying software and/or quality metrics reporting as part of their contractual requirements. Industry standards like ISO 9000 and industry models like the Software Engineering Institute’s (SEI) Capability Maturity Model Integrated (CMMI®) include measurement.  Companies are using metrics to better understand, track, control and predict software projects, processes and products.

The term software metrics means different things to different people. When we buy a book or pick up an article on software metrics, the topic can vary from project cost and effort prediction and modeling, to defect tracking and root cause analysis, to a specific

test coverage metric, to computer performance modeling. These are all examples of metrics when the word is used as a noun.

I prefer the activity based view taken by Goodman.  He defines software metrics as, "The continuous application of measurement-based techniques to the software development process and its products to supply meaningful and timely management information, together with the use of those techniques to improve that process and its products." [Goodman-93] Figure 1, illustrates an expansion of this definition to include software-related services such as installation and responding to customer issues. Software metrics can provide the information needed by engineers for technical decisions as well as information required by management.

If a metric is to provide useful information, everyone involved in selecting, designing, implementing, collecting, and utilizing it must understand its definition and purpose. This paper outlines twelve steps to selecting, designing and implementing software metrics in order to insure this understanding.