Software Architect's Handbook

Giving you the ability to predict software system qualities

When you look at a software architecture and its documentation, you can predict the software system's qualities. Making architecture decisions based on quality attributes makes it easier to fulfill those requirements. You want to start thinking about quality attributes as early as possible in the software development process as it is much more difficult (and costly) to make changes to fulfill them later. By thinking about them up front, and using modeling and analysis techniques, we can ensure that the software architecture can meet its non-functional requirements.

If you are not able to predict if a software system will fulfill quality attributes until it is implemented and tested, ...