REMINDER: This article is not a tutorial on applying and using statistics, but simply is a functional instruction on using the CESP documents themselves.
Open the file titled Control Charts and ensure that once opened, the tab “Instructions” is displayed.
This page will provide specific guidance on both the type of chart to use, out of the 5 available; Variable Charts, P Chart, NP Chart, U Chart and the C Chart. This will enable the user to chose the most appropriate chart for the circumstances.
Only yellow boxes are for data entry. All instructions and guidance are listed on the left, this includes where to enter relevant data, as well as data considerations for applying variable control charts.
Please note that if the Print function is selected on each of the chart tabs, it will only be the chart itself that will be printed, and not the input data.
Variable Charts
Figure 1 - Control Charts - Variable Charts
Variable control charts require a specified subgroup size*. A subgroup size >1 will generate an Xbar-R chart instead of the default I-MR.
Once the data in the large middle yellow column has been entered (either manually or copy/pasted from another source) the chart will be created, and subgroup size will be displayed in the top right. Control Limits are automatically calculated. The variable control charts apply all nelson rules available for statistical process control.
A maximum of 500 rows of data can be included. You can use the document or refer to your Capella trainer to provide guidance on minimum data points.
P Chart
Figure 2 - Control Charts - P Chart
The P Chart is used for attribute data when you want to plot % defectives with constant or unequal subgroup sample sizes*. It requires both count of defectives and the corresponding subgroup sample size for each count. This is so that it can calculate a % defectives. For example, if you inspected 100 documents, and found 14 were incorrect, your defectives would be 14, and your sample size would be 100, for a % defective of 14%.
Once the data in the large middle yellow columns have been entered (either manually or copy/pasted from another source) the chart will be created. Control Limits are automatically calculated. The attribute control charts apply only nelson rule 1 for statistical process control.
A maximum of 500 rows of data can be included. You can use the document or refer to your Capella trainer to provide guidance on minimum data points.
NP Chart
Figure 3 - Control Charts - NP Chart
The NP Chart is used for attribute data when you want to plot the count of defectives with constant subgroup sample sizes*. It requires the count of defectives and the constant sample size. For example, you inspect 50 documents for 10 days (500 total), and in the first day, you found 3 incorrect documents, your first data point will then be 3. You must then assume you are inspecting 50 each day and enter this as a constant sample size on the left.
Once the data in the large middle yellow columns have been entered (either manually or copy/pasted from another source) the chart will be created. Control Limits are automatically calculated. The attribute control charts apply only nelson rule 1 for statistical process control.
A maximum of 500 rows of data can be included. You can use the document or refer to your Capella trainer to provide guidance on minimum data points.
U Chart
Figure 4 - Control Charts - U Chart
The U Chart is used for attribute data when you want to plot defects per unit (DPU) with constant or unequal subgroup sample sizes*. It requires both count of defects and the corresponding subgroup sample size for each count. This is so that it can calculate a DPU. For example, if you inspected 100 documents, and found 28 individual errors across all of them, your defects would be 28, and your sample size would be 100, for a DPU (average defects per unit) of 0.28.
Once the data in the large middle yellow columns have been entered (either manually or copy/pasted from another source) the chart will be created. Control Limits are automatically calculated. The attribute control charts apply only nelson rule 1 for statistical process control.
A maximum of 500 rows of data can be included. You can use the document or refer to your Capella trainer to provide guidance on minimum data points.
C Chart
Figure 4 - Control Charts - C Chart
The C Chart is used for attribute data when you want to plot the count of defects with constant subgroup sample sizes*. It requires the count of defects and the constant sample size. For example, you inspect 50 documents for 10 days (500 total), and in the first day, you found 28 errors, your first data point will then be 28. You must then assume you are inspecting 50 each day and enter this as a constant sample size on the left.
Once the data in the large middle yellow columns have been entered (either manually or copy/pasted from another source) the chart will be created. Control Limits are automatically calculated. The attribute control charts apply only nelson rule 1 for statistical process control.
A maximum of 500 rows of data can be included. You can use the document or refer to your Capella trainer to provide guidance on minimum data points.
*A subgroup is a group of units that are created under the same set of conditions. If you collected items 5 at a time, your subgroup size would be 5. In most cases this is left as 1 (I.e. each data point is it's own independent observation).