01 · Purpose
Why and when to use it
Use it when a single-reference check cannot establish measurement suitability across small and large values.
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.
- Select traceable references across the working range.
- Take repeated independent readings at each level.
- Calculate mean bias at each reference.
- Plot bias against reference value and fit an appropriate relationship if justified.
- Assess practical effect, reference uncertainty and corrective action; verify the revised method.
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.
| Reference (g) | Mean reading (g) | Bias (g) |
|---|---|---|
| 50 | 50.02 | +0.02 |
| 100 | 100.06 | +0.06 |
| 150 | 150.10 | +0.10 |
04 · Interpretation
What the result tells you
The example bias increases by 0.04 g for each 50 g increase. This suggests a range-dependent error; subtracting one constant offset will not remove it across the whole range.
Completion check: A bias-versus-reference assessment with uncertainty and corrective decisions.
05 · Judgement
Mistakes and limitations
A non-significant slope is not proof of negligible bias. Check the size and uncertainty against the decision needs. Keep instrument linearity distinct from whether a process relationship is linear.
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.