Quality is a fundamental concept in software and information system development. It is also a complex and elusive concept. A large number of quality models have been developed for understanding, measuring and predicting qualities of software and information systems. It has been recognised that quality models should be constructed in accordance to the specific features of the application domain. This paper proposes a systematic method for constructing quality models of information systems. A diagrammatic notation is devised to represent quality models that enclose application specific features. Techniques of hazard analysis for the development and deployment of safety related systems are adapted for deriving quality models from system architectural designs. The method is illustrated by a part of web-based information systems.