These are typically captured using a control chart -- a statistical tool used in manufacturing or business to show the extent of the variation in a process.

In an attempt to improve the procedures for statistical process control many researchers have developed and proposed a variety of adaptive control charts in the last decade. The common characteristic ...

Using statistical control charts to analyze data from student evaluations of teaching. Decision Sciences Journal of Innovative Education, 1 (2): 259-272. McSweeney, L. A. 2006. Monitoring paper ...