In these videos Dr Robert Lloyd from the Institute for Healthcare Improvement introduces control charts, also known as Shewhart charts, which are used to display the measure of interest over time with the mean plotted as an X bar.
Unlike run charts control charts have control limits called the upper control limit and the lower control limit. These two boundaries help to define the variation in the process. The tighter the variation the tighter the control limits, the wider the variation the further apart the control limits.
Control charts part 1
Control charts part 2
