Chapter 5: Defect Analysis

Overview

Most organizations use the term quality to mean no, or few, defects. Some consider quality to mean meeting users' or customers' expectations. In the context of this book, both are correct. Any time that the software does not perform as the user expects, a defect has been encountered. It matters little to the user whether the problem is a coding error, a missed requirement, or just a function that would be nice to have but is absent.

It is no secret that defects occur in the SLC from the beginning of the concept phase through the final removal of the software system from use. Each defect that is found is expected to be corrected. The recording and tracking of defects ensures that all defects found are, in fact, addressed. Defect analysis applies to all defects and is intended to lead to the correction of current deficiencies and the elimination of defects in the future. Analysis of defects is the primary road to defect reduction. It can show where we started, where we are, and where we are going,

Defect analysis is the bridge between product-oriented software quality control activities and process-oriented software quality assurance activities of the SQS. Defect analysis is a combination of detecting product flaws so that they can be removed, and the analysis of defect and error data so future defects can be prevented. Defect reporting, tracking, and removal are adjuncts to configuration control (see Chapter 6).

While it useful to analyze defects in the system currently being developed, analyzing long-term trends also should be conducted to give clues to weak areas in the software development process. As a history of defect data is accumulated, it can provide indications of where modifications to the software development process can be effective. It is these problem analyses that provide the bridge from quality control-(detecting product errors) to quality assurance-(detecting process weaknesses).

This chapter concentrates on the quality assurance application of defect analysis and the metrics that can be developed.