Reviews are conducted to utilize the variety of perspectives and talents brought together in a team. The main goal is to identify defects within the stage or phase of the project where they originate, rather than in later test stages; this is referred to as “stage containment.” As reviews are generally greater than 65% efficient in finding defects, and testing is often less than 30% efficient, the advantage is obvious. In addition, since defects identified in the review process are found earlier in the life cycle, they are less expensive to correct.
Another advantage of holding reviews is not readily measurable. Reviews are an efficient method of educating a large number of people on a specific product or project in a relatively short period of time. Semiformal reviews (see Review Formats below) are especially good for this, and are often held for just that purpose. In addition to learning about a specific product or project, team members are exposed to a variety of approaches to technical issues (a cross-pollination effect). Finally, reviews provide training in, and enforce the use of, standards, as nonconformance to standards is considered a defect and reported as such.
The timing and the purpose of a review determine what type of review takes place, when it takes place, and how it is conducted. Reviews are performed during the development process, at the end of a phase, and at the end of the project.