FMEA

One of the most effective ways to use FMEA is to prioritize problem areas and fixes. To do this, ratings are assigned to the likely frequencies of the failures and how severe the effects will be in the event of a failure.

Note that in most cases these are relative ratings. Therefore, the rating of frequent depends on how often the procedure or task is performed. If the task is performed several times a day, such as changing a patient's IV, then a frequent failure could be once per day. If the task is performed only once per month, as in a transplant operation, then frequent could mean once or twice per year. The rating is relative to the number of opportunities.

The scales that are used are also relative. Some people use a scale of 1 to 5, others use 1 to 10. There is nothing magic in the choice. As long as the intervals between the assigned values are used reasonably, the same relative ranking should result from the assessment regardless of which scale is used.