Measures

Property	Measure
Speed	Processed transactions/second; User/Event response time; Screen refresh time.
Size	K Bytes; The number of RAM chips.
Ease of use	Training time; The number of help frames.
Reliability	Mean time to failure; Probability of unavailability; Rate of failure occurrence; Availability.
Robustness	Time to restart after failure; Percentage of events causing failure; Probability of data corruption on failure.
Portability	Percentage of target-dependent statements; Number of target systems.