What are the disadvantages of a rating system that combines inputs and outputs together?
Measurement of individual and organizational performance is typically based on results, not on preparation techniques, effort, etc. Consider what would happen if designers of college entrances tests, like the SAT or ACT, decided to rate students on both inputs and outputs. The exam scores would then be based on inputs-students’ demographics, family and socioeconomic characteristics, study habits, school staffing and funding, etc.-as well on outputs-how the student answered the specific exam questions. This would be a preposterous practice-which is precisely why it does not happen. Inputs are invaluable in designing a probing analysis of why some output scores are higher and lower, but data about them should not play any role in determining an output score.