Uncontrolled variation is the enemy to quality. It’s what experts W. Edwards Deming, Joseph M. Juran, et al, spent their professional lives stressing to industrial leaders. It remains the enemy to management because the concept of variation remains misunderstood.
A quality engineer whose job was to produce quality metric charts for monthly management meetings was disturbed that senior managers would react positively when a data point went the ‘right’ way but if a data point went the other way, the reaction was painful for everyone. Eventually, the quality engineer added control limits to each of the charts demonstrating sensitivity to variation and when to react to ‘out of spec’ variation. The result had a calming effect on the entire team. Morale improved as efforts were focused on identifying and eliminating special cause variation which subsequently resulted in business improvement.