01 · Purpose
Why and when to use it
Use it for clear comparisons between categories, such as shifts or issue types.
Who takes part?
The measurement owner works with people who understand the process and the recorded data. Statistical or measurement-system decisions should involve someone able to check the assumptions and study design.
02 · Application
How to apply it
Start with an agreed measurement purpose, explicit units and trustworthy observations. Identify missing cases and assumptions before calculating.
- Define the comparison question and categories.
- Choose counts or rates; include denominators when exposure differs.
- Calculate the selected summary consistently.
- Draw separated bars from a zero baseline and label units.
- Explain whether unequal volumes or sample sizes affect the comparison.
03 · Example
A worked measurement example
Original fictional teaching example. Small datasets illustrate the method; they are not proposed as sufficient study sizes. Supplied parameters are assumptions, not estimates from a real process.
| Shift | Late orders / total | Late percentage |
|---|---|---|
| A | 20 / 200 | 10% |
| B | 30 / 600 | 5% |
04 · Interpretation
What the result tells you
Shift B has more late orders in absolute count but a lower late percentage. Select the summary that answers the question; unequal workload matters.
Completion check: A labelled category comparison with an appropriate scale and denominator.
05 · Judgement
Mistakes and limitations
A difference between bars does not establish its cause or statistical reliability. Avoid truncated axes and mixing counts with percentages on the same scale.
07 · Reading
Sources and further reading
The tool list follows the accepted LeanTrainingLab overview and its reference to Six Sigma+Lean Toolset, second edition (Lunau, editor; Springer, 2013). The book chapters were not available for direct review during this build. Explanations, examples and worksheets are original teaching material. Further reading supplies professional background; local conventions are stated explicitly.