The multi-group individuals chart type is a specific spin on a fundamental SPC chart, the individuals chart. The multi-group individuals chart has the same specialties that a basic individuals chart does, but is particularly helpful when your individuals data has specific identifiers which may be used to segment the data to several subprocesses. Such an identifier could be something such as Shifts, Line numbers, or Locations was used to produce individuals data. After the segment is made in the individuals data, it makes it much easier to see if certain segments output results that differ in amounts of variation (Distance between limits), central tendency (Center line), or process instability (runs that continually ascend/descend or fall on one side of the mean line). Such investigations can help shine a spotlight on environments upstream that should first be considered for process improvement.
Control charts help to predict how a process will behave. If a reasonable number of data points all show as in-control on a control chart, you can make a useful prediction about your process. Unless the process is changed in some way, it will continue to produce results centered on this mean and varying within these limits.
If the control chart shows data points that are outside the limits or trends, or runs above or below the mean, this does not allow you to make a useful prediction about your process. This process is not stable and not predictable. Unless something is changed, we cannot be certain about the mean or the dispersion of data resulting from this process.
This predictive nature of control charts and their ability to minimize the mistakes described above are what makes them such valuable business tools.
When to use this chart:
1. When your process has data which allows segmentation such as locations, shifts, material types etc.
2. When you want to see if your process is stable and predictable;
3. When you want to see how planned change affects a process;
4. When the time order of the data values is preserved.
This chart is part of PI VIZpack™ by PQ Systems, a collection of eight process improvement charts for Power BI®. They provide a clear way to visualize and evaluate process behavior and performance. Get started with a free two-week trial today. After the trial, you may continue using the basic features or upgrade to the premium version. To learn more visit our website.