A usable system is one which enables users to perform their job effectively and efficiently.
Usability is definable and measurable.
Targets for efficiency and effectiveness can be set and achievement measured. Learnability Users require less training if systems are easy to learn and match the way in which they approach their tasks. User Satisfaction Staff turnover and absenteeism may be reduced if users feel that they are adequately supported in their jobs. User satisfaction is key to success. Memorability Users will require less training and will be able to return to peak levels of performance more quickly after absences if systems and processes are memorable.