According to American Heritage Dictionary, quality is defined as "an inherent or
distinguishing characteristic or a property".
The distinguishing characteristics of a software product are the cyclomatic
complexity, cohesion, function points, and lines of code. These characteristics of
a software product define the quality of the product.
• The US DOD (1988) defines software quality rather simply as: – The ability of a software product to satisfy its specified requirements. • The British Standards Institution (1986) has stated that:
– “Quality is in the eye of the beholder, a matter, of the client's judgment.” ⇒ Quality Standards and Procedures
The quality of software is said to be high if it meets the standards and procedures, defined for the product. Standards are criteria to which the products are compared. For example, there may be standards that govern the quality review process. Documentation standard design standard and code standard are the three types of standards that software projects usually follow.
Documentation standard specifies the form and content for planning, control, and product documentation. Design standards provide rules and methods for translating the software requirements into software design. The design standards are specified in the form and content of the product design.
Unlike documentation standard, code standard defines the language in which code should be written. The standard clearly mentions the structures, style conventions, and rules for data structures and interfaces that will be implemented in the project.
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Procedures are criteria to which the development and control processes are compared. Procedures are explicit steps followed in a process. Procedures need to be properly documented because they are needed for configuration management, nonconformance reporting, corrective action, testing, and formal inspections. Proper documentation of procedures is necessary because SQA activities rely on them for project compliance. Organizations normally enforce quality standards with the help of checklists, common error lists, and standards and guidelines. ⇒ Concepts
Product quality depends on its conformance to software requirements, development standards, and implicit requirements.
During software development, the quality of a product depends on the quality of the design.
The quality of product design, in turn, depends on how effectively the product designer captures the client requirements and specifications. At times, the client has some implicit requirements that are not captured in the requirements document. There are three things that guide requirements: want, desire, and wish. Usually, wants are captured explicitly in the requirements documents. However, if you manage to capture desires and wishes, the product becomes a great success. The product designer needs to state these implicit requirements clearly during analysis. The adherence to these implicit requirements is the key attribute that sets one product apart from another.
The product quality also depends on how strictly, and to what degree the developer adheres to design specifications. This is what the concept quality is meeting or exceeding our client's needs and requirements' means.
The product quality is said to be high if the product is manufactured according to design specifications.
⇒ Quality Control
Quality control is a series of review activities, such as: • Inspections
• Reviews and
• Tests, used throughout the SDLC of the software product
The objective of quality control is to find problems as early as possible and fix them.
Quality control ensures that the software product meets the requirements defined at every stage in its development.
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There is provision for feedback mechanism during quality control. Any slippage in meeting the requirements during the development process is communicated to the development team immediately.
Feedback ensures that errors or misses found during quality control are rectified as soon as they are detected.
During software development, quality control plays a valuable role by evaluating products against standards and specifications.
Quality control activities can be fully automated manual, or a combination of these. Quality control involves monitoring specific project results to determine if:
– They comply with relevant quality standards
– Identifying ways to eliminate causes of unsatisfactory results. Project results include both:
– Product results, such as deliverables, and
– Project management results, such as cost and schedule performance. ⇒ Quality Factors
There are a number of factors that determine the quality of a software product. These factors can be measured either directly or indirectly. McCall (MCC77) and his colleagues proposed some software quality factors based on three most important aspects of a software product:
1. Product operation 2. Product revision and 3. Product transition 1. Product Operation Factors
The product operation factors determine the quality of software when a program is executed. Good quality software is not only correct and reliable but also delivers correct performance in all circumstances. Some of the factors of product operation are correctness, reliability, efficiency, integrity, and usability. You can look at the factor description in Table 1.
Table 1: Product Operation Factors
Correctness Accuracy of the program and the extent to which it fulfills design specifications Reliability Extent to which the program is secure and its ability to recover quickly from failure.
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Efficiency Performance of the program and its ability to perform tasks within a time frame
Integrity Ability of the program to take care of security and the extent to which it can prevent unauthorized.
Usability Ease with which a user can learn, operates, and uses the program.