Setting Quality Criteria

The customer may define quality standards as a set of features. For example:

• Whenever the user makes a mistake, a user-friendly error screen appears.

• It's impossible to crash the server via the user interface.

• The system can handle a hundred concurrent logins.

• The system will stay up 99.995% of the time.

The customer asks for a certain level of quality, and the programmers account for that in estimating the risk and effort of the stories. Many quality criteria can become stories on their own. For example, the customer could write a story saying the system should handle all exceptions and print out a user-friendly error message.