Control Charts are an important tool for analyzing your process. In this post I show you how you can create a lead time Control Chart in Microsoft Excel 2010.
In this example the control limits are based on the standard deviation function in Excel. This may or may not be the correct way to calculate your control limits of your data
Let’s get started.
1. Create a new workbook
2. Rename “Sheet1” to “Data”
3. Add the columns “Id” , ”Title”, “StartDate”, “EndDate”, “LeadTime”, “Type”, “Comments”
4. Select all the columns and the row below
5. Open the “Insert tab” in the Excel ribbon
6. Create a table by clicking on the “Table” button on the Excel ribbon
7. Check “My table has headers” and click OK
8. Rename table to “LeadTimeTable”
9. Format the header row to make more useable
10. Format the columns “StartDate” and “EndDate” as date columns
12. Add the formula “=[EndDate]-[StartDate]” in the “LeadTime” column
12. Format the “LeadTime” column as number column
13. Add some example data
14. Switch to the “Sheet2” worksheet and rename it to “Criterias”
Now we will create criteria’s that will be used to select the appropriate rows from the “LeadTimeTable” on the “Data” sheet when we do the calculations for the control chart.
15. Add a label for your criteria and add it to the “Criterias” sheet
16. Copy the header row form the “Data” sheet as shown
17. Add the criteria to get all features by adding the formula =”=Feature” in the feature column
18. Select the all the headers and the criteria row below
19. Open the “Insert tab” in the Excel ribbon
20. Create a table by clicking on the “Table” button on the Excel ribbon
21. Check “My table has headers” and click OK
22. Rename table to “FeatureCriteria1”
23. Switch to the “Sheet3” worksheet and rename it to “Features”
24. Add the columns “EndDate”, “Lead time”, “Average Lead Time”, “OneSigma”, “Upper Control Limit”, “Lower Control Limit”
25. In the “EndDate” column add the formula =LeadTimeTable[@EndDate]
26. In the “Lead time” column add the formula =IF(LeadTimeTable[@Type] = “Feature”;LeadTimeTable[@LeadTime];NA())
This formula will get the “Lead time” if the type is a feature and sets a #N/A if not. This will prevent non feature values to be plotted on the control chart.
27. In the “Average lead time” column add a DAVERAGE formula as shown
This formula will calculate the average lead time for all rows matching the “FeatureCritera1”
28. In the “OneSigma” column add a DSTDEVP formula as shown
This formula will calculate the standard deviation for the lead time of the population matching the “FeatureCritera1”
29. In the “Upper Control Limit” column add the formula =C2+D2
This formula adds one sigma or one confidence interval to the average lead time. This will be the upper control limit that is approximately 70% of the population.
30. In the “Lower Control Limit” column add the formula =C2-D2
This formula subtracts one sigma or one confidence interval from the average lead time.
31. Format the columns to make it more usable
32. Select all the columns and the row with the formulas
33 Open the “Insert tab” in the Excel ribbon
34. Create a table by clicking on the “Table” button on the Excel ribbon
35. Check “My table has headers” and click OK
36. Rename table to “FeatureTable”
37. Now expand the “FeatureTable” to the same row count as in the “LeadTimeTable”
We are now ready to create the Feature Lead Time Control Chart.
38. Select all but the “OneSigma” column
39. Insert a “Scatter with only Marker” chart and move it to a new sheet named “FeaturesControlChart”
40. Select the “Average Lead Time” series by selecting one of its markers
41. Right click and select “Change Series Chart Type”
42. Select a “Line” chart
43. Now repeat step 31 to 33 for “Upper Control Limit” and “Lower Control Limit”
The chart should now look something like this
44. Now format the chart to make it clear what is inside the control limits. It could look something like this
Now you have a lead time control chart! Now you can replace the example data and add your own data. Just add a new row for every delivered feature. Remember to also update number of rows of the “FeatureTable” (see step 28) or the cart will not be updated correctly.
You can also add other work item types and other criteria’s for the calculations as you use it.
Download example file here: Control Chart Example.xlsx