oyees; each are measured by Production, Efficiency, Dirct and Indirect time over a 40 hour work week, but are not assigned to the same weighted units?...

If you have 12 employees; each are measured by Production, Efficiency, Dirct and Indirect time over a 40 hour work week, but are not assigned to the same weighted units? How can you fairly measure one's progress in a productivity report at the end of 30 days for each empoyee; than determine who you are the star producers? Is this fair, or not? If so, why?