Why measurements don’t always bring opposing views together

Can measurements resolve opposing views about the truth or falsehood of controversial claims?   That indeed is one of the most important purposes of measurement.  But it does not always work out that way. Take a chemical company at which plant managers and laboratory staff around the world were at loggerheads over measurements of product brightness. [...]

More circular reasoning on statistical process control

After my last post I received a number of comments on the website KPIExperts.  Most of them completely misunderstood my point, and their misunderstanding was so fundamental that rather than reply to their comments individually I decided to write a new post.  I myself have trained thousands of people in SPC over more than two [...]

Circular Reasoning in Statistical Process Control

In a Statistical Process Control (SPC) chart, measurements are plotted on a chart with upper and lower “control limits.” The idea is to compare the plotted points with the limits to see if a process is stable, and to identify “special” causes of variation.  The control limits are supposed to indicate when action should be taken [...]