Subgroups are used where there are multiple data points for a single date. A subgroup is a selection of points form a single date that is used to calculate the value of a point plotted on the chart. The same number of points is selected for each day. If a day has less than the chosen subgroup size then that point is not included in the chart. When CapChart determines that the data is suitable for Subgroups a new menu item appears called Subgroup. Under this menu is a options submenu which when selected will display the Subgroup Options dialog box shown below.

The subgroup options dialog allows you to change the subgroup size. It indicates the number of points available for each subgroup size. Other options include whether to treat the data as subgroups , How to select the subgroup and to show all points. Selecting show all points will display both points which have enogh data for the subgroup size and also display a point for the average of those that don't have sufficient data. Those which don't have the number for the subgroup size are not included in the calculation of the limits. Below are examples of a subgroup chart with only points with correct subgroup size and also both.