Metrics in Software Development - Quality metrics

Software Quality Metrics focus on the process, project and product. By analyzing the metrics the organization the organization can take corrective action to fix those areas in the process, project or product which are the cause of the software defects.
The quality of the product is ensured by the following metrics :
- Number of defects found per KDSI (also known as defect density).
- Number of changes requested by the customer after the software is delivered.
- MTBF(Mean Time Between Failures).
- MTTR(Mean Time To Repair) i.e. the average time that is required to remove a detect after it has been detected.

Common software metrics include bugs per line of code, code coverage, cohesion, coupling, cyclomatic complexity, function point analysis, number of classes and interfaces, number of lines of customer requirements, order of growth,source lines of code, Robert Cecil Martin’s software package metrics.

To measure the quality of the output of a development phase, the SQA team has to define the metrics. For instance, during the requirements engineering phase, SRS document is written. Then design, implementation, and testing are done. While doing the design or implementation or while carrying out the testing, the SRS document may have to be changed. The number of changes made to the SRS document can be a metric to measure the quality of the requirements engineering process.
Although there are many measures of software quality, correctness, maintainability, integrity and usability provide useful insight.