What happens when we measure the same thing and get different values? How can we ever use such a measurement system to measure different things? By thinking of measurements as the product and the measurement procedure as the process we can use the techniques of statistical process control (SPC) to address the problems of complex measurement systems.

When your process outcomes are not what you expect them to be it is common to adjust the process. This is not always appropriate. To understand when adjustments are appropriate, and when they are inappropriate, we will need to learn how to distinguish between the noise contained within the data and a signal that an adjustment is needed. Both the problem and the solution will be illustrated by an example from my own experience.

There are two basic ideas or principles that need to be respected when creating a chart for individual values and a moving range (an XmR chart). This column will explain and illustrate these two principles for effective XmR charts.

I n my September column, I showed how the normal distribution is the distribution of maximum uncertainty. Now I will expand on that theme and answer the questions generated by that column.