CHAPTER-13QUALITYCONCEPTSSoftware Engineering: A Practitioner’s Approach, 7th editionOriginated by Roger S. PressmanSOFTWAREENGINEERING1Software School, Fudan University Spring Semester, 2016
SOFTWAREQUALITY¢In 2005, ComputerWorld[Hil05] lamented that “bad software plagues nearly every organization that uses computers, causing lost work hours during computer downtime, lost or corrupted data, missed sales opportunities, high IT support and maintenance costs, and low customer satisfaction. ¢A year later, InfoWorld[Fos06] wrote about the “the sorry state of software quality” reporting that the quality problem had not gotten any better.¢Today, software quality remains an issue, but who is to blame? Customers blame developers, arguing that sloppy practices lead to low-quality software. Developers blame customers (and other stakeholders), arguing that irrational delivery dates and a continuing stream of changes force them to deliver software before it has been fully validated.2Software School, Fudan University Spring Semester, 2016
QUALITY¢The American Heritage Dictionarydefines qualityas “a characteristic or attribute of something.” ¢For software, two kinds of quality may be encountered: Quality of design encompasses requirements, specifications, and the design of the system. Quality of conformance is an issue focused primarily on implementation.User satisfaction = compliant product + good quality + delivery within budget and schedule3Software School, Fudan University Spring Semester, 2016
QUALITY—A PHILOSOPHICALVIEW¢Robert Persig [Per74] commented on the thing we call quality:Quality . . . you know what it is, yet you don't know what it is. But that's self-contradictory. But some things are better than others, that is, they have more quality. But when you try to say what the quality is, apart from the things that have it, it all goes poof! There's nothing to talk about. But if you can't say what Quality is, how do you know what it is, or how do you know that it even exists? If no one knows what it is, then for all practical purposes it doesn't exist at all. But for all practical purposes it really does exist. What else are the grades based on? Why else would people pay fortunes for some things and throw others in the trash pile? Obviously some things are better than others . . . but what's the betterness?. . . So round and round you go, spinning mental wheels and nowhere finding anyplace to get traction. What the hell is Quality? What is it?4Software School, Fudan University Spring Semester, 2016
QUALITY—A PRAGMATICVIEW¢The transcendental viewargues (like Persig) that quality is something that you immediately recognize, but cannot explicitly define. ¢The user viewsees quality in terms of an end-user’s specific goals. If a product meets those goals, it exhibits quality.