Control rules take advantage of the normal curve in which 68.26 percent of all data is within plus or minus one standard deviation from the average, 95.44 percent of all data is within plus or minus ...

Using Microsoft Excel you can create charts based on the data and formulas entered in a worksheet. Enter a sample range of numbers in Excel as if you were at an event asking people their ages, for ...

Here is a quick overview for an understanding a standard deviation chart data set. You can see how the examples of the data will fall within one standard deviation of the mean for approximately 68% of ...

The following statements create and s charts for the diameter data: title f=qcfont4 'X ' f=swiss 'and s Chart for Diameter'; symbol v=dot c=salmon; proc shewhart data=toolwear; xschart diameter*hour / ...

When you are working with subgrouped data, it can be helpful to accompany a cusum chart for means with a Shewhart s chart for monitoring the variability of the process. This example creates this ...

Control charts that are properly constructed and maintained prevent false out-of-control signals and provide a useful method for monitoring a process. Process control is and has been an important ...

In response to my article, Is the Stock Market Too Concentrated?, which relied upon standard-deviation calculations to assess investment risk, a reader wrote: “My problem [with your argument] is ...