Role of Metrics and Measurement in software development

• The terms measure, measurement, and metrics are often used interchangeably, it is important to note the subtle differences between them. Because measure can be used either as a noun or a verb, definitions of the term can become confusing.
• When a single data point has been collected (e.g., the number of errors uncovered in the review of a single module), a measure has been established.
• Measurement occurs as the result of the collection of one or more data points (e.g., a number of module reviews are investigated to collect measures of the number of errors for each).
• A software metric relates the individual measures in some way (e.g., the average number of errors found per review or the average number of errors found per person-hour expended on reviews).
• Measurements in the physical world can be categorized in two ways: direct measures and indirect measures.

1.       Direct measures of the product include lines of code (LOC) produced, execution speed, memory size, and defects reported over some set period of time. Indirect measures of the product include functionality, quality, complexity, efficiency, reliability, maintainability.

• The basic purpose of metrics at any point during a development project is to provide quantitative information to the management process so that the information can be used to effectively control the development process. Unless the metric is useful in some form to monitor or control the cost, schedule, or quality of the project, it is of little use for a project.
• There are very few metrics that have been defined for requirements.