Variation

Natural variation is present in every part of our lives. For example, there is huge variation amongst humans in:

• birth weight
• height
• athletic ability
• colour of hair and eyes
• weight etc.

In just the same way, there will always be variation in any commercial process (and its inputs and outputs). Users of SPC seek to minimise this variation, both to increase the probability of the process delivering a satisfactory output and to minimise total quality cost.