_MEAN_ process mean (value of central line on box chart) _R_ value of central line on R chart _S_ value of central line on s chart A subgroup standard deviation variable is included if you specify the ...

Steven Nickolas is a writer and has 10+ years of experience working as a consultant to retail and institutional investors. Portfolio variance is a measure of the dispersion of returns of a portfolio.

The previous example illustrates how you can create s charts using raw data (process measurements). However, in many applications, the data are provided as subgroup summary statistics. This example ...

Will Kenton is an expert on the economy and investing laws and regulations. He previously held senior editorial roles at Investopedia and Kapitall Wire and holds a MA in Economics from The New School ...

For a given data set, standard deviation measures how spread out the numbers are from an average value. This measurement of average variance has a prominent place in many fields related to statistics, ...