The severity of a usability problem is a combination of three factors:

  • The frequency with which the problem occurs: Is it common or rare?
  • The impact of the problem if it occurs: Will it be easy or difficult for the users to overcome?
  • The persistence of the problem: Is it a one-time problem that users can overcome once they know about it or will users repeatedly be bothered by the problem?

the following 0 to 4 rating scale can be used to rate the severity of usability problems:

0 = I don’t agree that this is a usability problem at all
1 = Cosmetic problem only: need not be fixed unless extra time is available on project
2 = Minor usability problem: fixing this should be given low priority
3 = Major usability problem: important to fix, so should be given high priority
4 = Usability catastrophe: imperative to fix this before product can be released

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