For example, in the following statements, the data set DETSUM2 must contain a subgroup standard deviation variable named WEIGHTS: title 'Median Chart for Weights'; symbol v=dot; proc shewhart ...

A behind-the-scenes blog about research methods at Pew Research Center. For our latest findings, visit pewresearch.org. Academic survey researchers tend to differ ...

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