Before digging into the ABCs for software user interfaces, it is a good idea to review factors that drive user satisfaction. User satisfaction is influenced by a small number of factors that are represented in an equation such as the following:
The uppercase factors are the most significant. We can all find examples where a product is not usable if the following are true:
Key functional features are missing.
The user interface is missing key features, has poor appearance and behavior, or imposes major interaction demands on users.
Response time and throughput are slow.
The system crashes, or causes work or data to be lost.
The factors in the equation can be refined furtherfor example, user interface has components related to appearance, behavior, user knowledge demands, and user interaction demands. Other factors can certainly be added to the equation. Usability factors must be included in the ABCs to ensure that all relevant factors are in the tickler list.