Control Chart

A statistical graph that plots the continuous data points over time to define observations (the actual plotted data points), the mean (a.k.a. average), lower control limit (LCL), upper control limit (UCL), and special cause tests. The purpose of this chart is to visually depict the process performance to see how "in control" it is and highlight any areas that aren't in control (reflected as special causes).
Related StatStuff Video: 
   -Section 5-Measure Phase, Lesson #16 - Testing for Special Cause Variation