Where is Variability Coming From and What Have We Done to Minimize It?

This blog post was written by Lynn D. Torbeck

Textbooks and journal articles treat common cause variation as if it is an inevitable fact of nature and beyond our control: “In any production process, regardless of how well-designed or carefully maintained it is, a certain amount of inherent or natural variability will always exist. This natural variability or ‘background noise’ is the cumulative effect of many small, essentially unavoidable causes” [Emphasis added]. This attitude cuts off thoughts of trying to reduce variation. But, with some reflection, there are several ideas and techniques that can begin to help reduce common cause variation.

Aiming for and hitting the target, whether it is x, y or z, seems a simple idea, but it could be argued that it is everybody’s responsibility to know what the target is and to do everything possible to hit that target every time. One person achieving the target infrequently doesn’t help. But 400 people hitting targets a dozen times a day can have a dramatic effect on reducing variability. The target could be something as simple as setting the temperature on a dryer or as complex as a management objective. Keep in mind that a specification range is not a playground for manufacturing.