Control charts, also known as Shewhart charts (after Walter A. Shewhart) or process-behavior charts, in statistical process control are tools used to determine if a manufacturing or business process is in a state of statistical control. You can read more about control charts at Wikipedia (http://en.wikipedia.org/wiki/Control_chart).

Control charts are widely used in healthcare. A simple example of a time series chart using an upper and lower bound for a control range is shown below. The sample control chart is modeled after a control chart found in the the JAMA article “Association Between Quality Improvement for Care Transitions in Communities and Rehospitalizations Among Medicare Beneficiaries” (link: http://jama.jamanetwork.com/article.aspx?articleid=1558278). It models a graph in “Figure 1. Process Control Charts for 30-Day All-Cause Rehospitalizations per 1000 Medicare Beneficiaries per Quarter, 2006-2010” which can be seen below