Let us now do this activity on Minitab. I have added this data on a spreadsheet and uploaded it in the resources section of this lecture. Please download the data and paste it to Minitab. Choose stat, control charts, variable chart for individuals. I Mr. I repeat, choose that.

Control charts variable chart for individuals. I Mr. In variables, enter wait. Click I Mr options. Then click the test tab. Choose perform all tests for special causes from the drop down Then click OK.

In each dialog box here you go. This is the IMR chart. Let's talk about its influence. Now, you will observe that there are two charts, one is called the individual value, and the second is the moving range chart. Individual value chart plots individual observations, whereas the moving range chart is a subtraction of two consecutive data points. As you observe the individual value chart, there is an upward shift in the weight of cold cream bottoms around data point 20 or 21.

There is an obvious shift in process level pattern on the chart for individuals. Note that the moving range chart also react to this level shift with a single large spike at sample 20 this Spike on the moving range chart is sometimes helpful in identifying exactly where the process shift has occurred. Which chart should we look at individuals or moving range, some authorities recommend not constructing and plotting the moving range chart. They point out that the moving range chart cannot really provide useful information about the shift in process variability. My feeling is that initially, you derive your findings only using the individual's chart. As you gain experience in interpreting these charts, you can then start looking at the moving range chart.

Okay. Coming back to the interpretation of this chart, this process is out of control. The team needs to investigate why the shift in this process has occurred. That brings us to the end of this lecture. You will now go through an activity