Software Metrics
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A metric quantifies a characteristic of a process or product. Metrics can be directly observable quantities or can be derived from one or more directly observable quantities. Examples of raw metrics include the number of source lines of code, number of documentation pages, number of staff-hours, number of tests, number of requirements, etc. Examples of derived metrics include source lines of code per staff-hour, defects per thousand lines of code, or a cost performance index.

Software metrics are numerical data related to software development. Metrics strongly support software project management activities. They relate to the four functions of management as follows:
1. Planning - Metrics serve as a basis of cost estimating, training planning, resource planning, scheduling, and budgeting.
2. Organizing - Size and schedule metrics influence a project's organization.
3. Controlling - Metrics are used to status and track software development activities for compliance to plans.
4. Improving - Metrics are used as a tool for process improvement and to identify where improvement efforts should be concentrated and measure the effects of process improvement efforts.
The term indicator is used to denote a representation of metric data that provides insight into an ongoing software development project or process improvement activity. Indicators are metrics in a form suitable for assessing project behavior or process improvement. For example, an indicator may be the behavior of a metric over time or the ratio of two metrics. Indicators may include the comparison of actual values versus the plan, project stability metrics, or quality metrics. Examples of indicators used on a project include actual versus planned task completions, actual versus planned staffing, number of trouble reports written and resolved over time, and number of requirements changes over time.

Indicators are used in conjunction with one another to provide a more complete picture of project or organization behavior. For example, a progress indicator is related to requirements and size indicators. All three indicators should be used and interpreted together.