XmR charts monitor the outputs of processes to provide a rapid and reliable means of detecting change in those outputs. Walter A. Shewhart was the statistician who invented this style of chart, back in 1924. He used them to monitor the production quality of underground transmission equipment at the Western Electric Company. Since then, these charts have rocked the world.
What many managers today still don't realise is that Shewhart's approach to analysing data for manufacturing performance is just as applicable and transformational for non-manufacturing performance results. We can use Shewhart's charts to monitor:
Dr Donald Wheeler, a renowned statistician of our time, wrote Understanding Variation: The Key to Managing Chaos on this very topic. Wheeler introduced the use of the XmR chart for management data, or, as we call it, performance measurement. His closing remarks in this best-selling management book are worth repeating here:
Millions of people have proven, by their own experiences, over the past 60 years, that Shewhart's control charts work. This approach to understanding and using data is not on trial. The question is not whether or not the techniques will work — but rather whether or not you will make them work.
The power of XmR charts is how clearly and accurately they show us signals ...