Lesson 01 · 10–15 minutes · Available now
Understand process variation
A process does not produce exactly the same result every time. Before comparing averages, investigate how individual observations and their short-term differences behave.
Question: Does this sample show evidence that the process may have changed, or does it look consistent with its estimated historical limits?
Try it in VariScout
- Open VariScout and select Start with the example.
- Click Explore variation. In the dialog, select FillWeight.
- Leave the default I-MR settings and run the analysis. Both Individuals and Moving Range charts appear.
- Read the center line and control limits. Check whether any points exceed the limits. Examine the Moving Range chart for unusually large changes between adjacent observations.
- Try the classic menu route below and confirm that it opens the same dialog.
Open the real analysis
The example dataset is included in the app. All calculations run locally in your browser.
Launch VariScout ↗What are the two charts saying?
Individuals (I)Shows the observations in their recorded order. The center line estimates the historical level. Limits describe expected behavior under the chosen assumptions, not product specifications.
Moving Range (MR)Shows the absolute difference between successive measurements. A large moving range may signal a sudden change even when the individual values look ordinary.
Think before concluding
- What happened when the largest moving range occurred?
- Would shuffling the observations change this analysis? Why?
- What additional process knowledge or data would you want before recommending an intervention?
Important: An I-MR chart estimates historical control limits. It is not a capability analysis, and control limits are not customer specification limits. This pilot supports Test 1 and an optional nine-point run test; it is not a complete Minitab implementation.
Next topics — distributions and group comparisons — are planned, not yet available.