Introducing measurable quality requirements: a case study

In this paper a case study on improving requirements engineering is presented. Improving requirements engineering was initiated in a department at Ericsson Eurolab after an analysis had shown that many of the problems in software development had their root cause in insufficient understanding of the customer and in unclear requirements. A method-in respect to Tom Gilb who supported us in this field-called Gilb Style was introduced. This method focuses on: quality (or non-functional) requirements; quantification; strict separation between design and requirements; constraints and assumptions. After a year of experience and several projects using this method, the findings are presented. The biggest benefit in using this method is a change of culture towards requirements. This change is not limited to requirements specifications for software but includes e.g. requirements on internal service functions. The common understanding of requirements has drastically increased. Several positive side effects include more effective inspections, introduction of weekly reviews, simpler definition of test cases. The biggest problems were communication problems to (internal) customers, who did not participate in the introduction of the method.