A few months back I received a phone call from an old friend.  After we had finished catching up for a bit he began describing to me how he had his employees calculate the yield of his pizza's.  each day the employees would mark how much came out and how much was put in.  The employee would then divide the out number by the in number giving him the yield percentage.  Sound familiar?  The method that was being used to calculate yield is known as traditional yield calculation.  Out of curiosity I asked him, "what is your yield percentage?"  He then shared with me that his yield for each day was always right about 96%.  So what was the issue?  96% production rate is not the best, but it's not the worst either.  That's when he mentioned that things didn't seem to add up.