View and Analyze Created Control Charts
Explanation
This activity is used to view and analyze any created control charts.
Open the control chart that you want to view on the p Chart, np Chart, c Chart, u Chart Xbar and R
Chart, Xbar and S Chart or X and MR Chart page. These pages can also be
accessed from the Control Charts page.
- p Chart - Gives information about the proportion of nonconforming units.
- np Chart - Gives information about the number of nonconforming units.
- c Chart - Gives information about the number of nonconformities.
- u Chart - Gives information about the number of nonconformities per unit.
- Xbar and R Chart - Gives information about the average and the range of the result set of
each analysis selected in the graph.
- Xbar and S Chart - Gives information about the average and the standard deviation of the
result set of each analysis selected in the graph.
- X and MR Chart - Gives information about individual results and moving ranges for each
analysis selected in the graph.
Control charts are used to analyze a process or its outputs and take appropriate actions to achieve and maintain
a state of statistical control. A process is in statistical control ("in control") when all special
causes of variation have been eliminated and only common causes remain, i.e., observed variation can be attributed
to a constant system of chance causes.
Several statistical tests (alarm rules) can be used to determine whether a control chart is "in
control" or "out of control":
- Out of Specification: An alarm rule violation will be triggered when a point in the control
chart is above Inner Max or Outer Max or below Inner Min or Outer Min.
- Above Upper Control Limit: An alarm rule violation will be triggered when a point in the
control chart is above the Upper Control Limit (UCL).
- Below Lower Control Limit: An alarm rule violation will be triggered when a point in the
control chart is below the Lower Control Limit (LCL).
- 2 out of 3 beyong 2 sigma: An alarm rule violation will be triggered when at least two out
of three successive points in the control chart on the same side of the centerline (CL) are beyond the 2 sigma
limit.
- 4 out of 5 beyond 1 sigma: An alarm rule violatin will be triggered when at least four out
of five successive points in the control chart on the same side of the centerline (CL) are beyond the 1 sigma
limit.
- 15 at or within 1 sigma: An alrm rule violation will be triggered when 15 successive point
in the control chart are at or within 1 sigma.
- 8 outside 2 sigma: An alarm rule violation will be triggered when eight successive points in
the control chart are outside +2 or -2 sigma.
- 8 below or above the centerline: An alarm rule violation will be triggered when eight
successive points in the ocntrol chart are below or above the centerline.
- Runs up/ down of length 8 or greater: An alarm rule violation will be triggered when eight
successive points in the control chart are in ascending or descending order.
One or more of these alarm rules may have been activated for the control plan line (data point). If an alarm
rule violation occurs for an activated alarm rule, information about the alarm rule violation will be displayed in
the control chart.
If you want to see all the measurement data used for the calculations of the control chart, click Sample
Data. If you want to view the analysis numbers that were excluded when the control charts were created, click
Not Included Sample Data. The graph can be printed by clicking Print Graph. To view the
control chart setup used to create the chart, click View Setup.
Prerequisites
At least one control chart of the type you want to view must exist.
System Effects
As a result of this activity, any created control chart can be viewed and analyzed.