For control charts with unequal subgroup sizes, the center line, control limits and zones may vary. In this case, the tests apply to a standardized control chart where the points are the number of standard deviation units from the center line. Such a control chart has a constant center line at 0, and upper and lower control limits of +3 and -3 Keep emotion (and error) out of your measure evaluations with these step-by-step instructions. Control Chart Examples: How To Make Them Work In Your Organization. Budget: You can use your control charts to examine your percentage of spend each month. If you spend over 15% of your budget in one particular spring month, that is extremely helpful A control chart indicates when your process is out of control and helps you identify the presence of special-cause variation. When special-cause variation is present, your process is not stable and corrective action is necessary. Control charts are graphs that plot your process data in time-ordered sequence. Most control charts include a center