There are formal and informal reviews. Informal reviews occur spontaneously among peers; the reviewers do not necessarily have any responsibility and do not have to produce a review report. Formal reviews are carefully planned meetings in which reviewers are held responsible for their participation, and a review report is generated that contains action items.

The spectrum of review ranges from very informal peer reviews to extremely formal and structured inspections. The complexity of a review is usually correlated to the complexity of the project. As the complexity of a project increases, the need for more formal reviews increases.

Structured Walkthroughs

A structured walkthrough is a presentation review in which a review participant, usually the developer of the software being reviewed, narrates a description of the software, and the remainder of the group provides feedback throughout the presentation. Testing deliverables such as test plans, test cases, and test scripts can also be reviewed using the walkthrough technique. These are referred to as presentation reviews because the bulk of the feedback usually occurs only for the material actually presented.

Advance preparation of the reviewers is not necessarily required. One potential disadvantage of a structured walkthrough is that, because of its informal structure, disorganized and uncontrolled reviews may result. Walkthroughs may also be stressful if the developer is conducting the walkthrough.


The inspection technique is a formally defined process for verification of the software product throughout its development. All software deliverables are examined at defined phases to assess the current status and quality effectiveness, from the requirements to coding phase. One of the major decisions within an inspection is whether a software deliverable can proceed to the next development phase.

Software quality is achieved in a product during the early stages when the cost to remedy defects is 10 to 100 times less than it would be during testing or maintenance. It is, therefore, advantageous to find and correct defects as near to their point of origin as possible. Exit criteria are the standard against which inspections measure completion of the product at the end of a phase.

The advantages of inspections are that they are very systematic, controlled, and less stressful. The inspection process promotes the concept of egoless programming. If managed properly, it is a forum in which developers need not become emotionally protective of the work produced. An inspection requires an agenda to guide the review preparation and the meeting itself. Inspections have rigorous entry and exit requirements for the project work deliverables.

A major difference between structured walkthroughs and inspections is that inspections collect information to improve the development and review processes themselves. In this sense, an inspection is more of a quality assurance technique than walkthroughs.

Phased inspections apply the PDCA (Plan, Do, Check, and Act) quality model. Each development phase has entrance requirements; for example, how to qualify to enter an inspection and exit criteria, and how to know when to exit the inspection. In-between the entry and exit are the project deliverables that are inspected.

The Plan step of the continuous improvement process consists of inspection planning and preparing an education overview. The strategy of an inspection is to design and implement a review process that is timely, efficient, and effective. Specific products are designated, as are acceptable criteria, and meaningful metrics are defined to measure and maximize the efficiency of the process. Inspection materials must meet inspection entry criteria. The right participants are identified and scheduled. In addition, a suitable meeting place and time are decided. The group of participants is educated on what is to be inspected and their roles.

The Do step includes individual preparation for the inspections and the inspection itself. Participants learn the material and prepare for their assigned roles, and the inspection proceeds. Each review is assigned one or more specific aspects of the product to be reviewed in terms of technical accuracy, standards and conventions, quality assurance, and readability.

The Check step includes the identification and documentation of the defects uncovered. Defects are discovered during the inspection, but solution hunting and the discussion of design alternatives are discouraged. Inspections are a review process, not a solution session.

The Act step includes the rework and follow-up required to correct any defects. The author reworks all discovered defects. The team ensures that all the potential corrective actions are effective and no secondary defects are inadvertently introduced.

By going around the PDCA cycle for each development phase using inspections, we verify and improve each phase deliverable at its origin and stop it dead in its tracks when defects are discovered (see Figure 6.4). The next phase cannot Start until the discovered defects are corrected. The reason is that it is advantageous to find and correct defects as near to their point of origin as possible. Repeated application of the PDCA results in an ascending spiral, facilitating quality improvement at each phase. The end product is dramatically improved, and the bewildering task of the software testing process will be minimized; for example, a lot of the defects will have been identified and corrected by the time the testing team receives the code.