Fig. 2

Control chart and control chart zones. A control chart is a graphical representation of a process over time, for instance weekly ASRM scores, where control limits defined by the number of standard deviations from the mean are highlighted. The areas between the control limits define control zones used to subsequently apply control rules that will allow the user to identify observations potentially showing a special cause variability and not simply random variability. This study considered only control zones above the mean, because in the context of bipolar disorder unusually high mood scores are of greater interest than low ones. This figure shows an X-bar chart for randomly generated ARSM scores (mean = 5, SD = 3.3)