Improving Product Reliability and Software Quality, 2nd Edition
by Mark A. Levin, Ted T. Kalal, Jonathan Rodin
9Software Quality Goals and Metrics
9.1 Setting Software Quality Goals
It is not possible to remove every defect from a software release. Even if it were, it is not economically feasible to do so. Software quality goals should be set by examining the software quality needs based on a return on investment (ROI) analysis for the investment in quality.
Software quality needs are not the same for all products. It may not even be the same for all parts of a single product. So, how does an organization determine how much to invest in software quality and even which parts of the product to focus those efforts on to ensure the most bang for the buck?
When determining quality goals, one needs to take into account the impact of the defect and the cost to fix the defect. Acceptable quality targets might be lower for products (or product components) where the defects have minimal impact to the customer or are not costly to fix. On the other hand, quality targets should be high for products (or components) where the defects have a significant impact or are very costly to fix.
At one extreme, a typo on a web page might be an example of a low‐impact, easy‐to‐fix defect. The developer can make an easy change and the defect can be remedied in a very short period of time. In many cases, this typo would have no material or financial impact whatsoever.
At the other end of the spectrum, a defect in a medical device might result in the death of a user. This defect escape is expensive, potentially ...