Calibration · Glossary

What are Type A and Type B Uncertainty?

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Type A and Type B uncertainty are the two ways of evaluating uncertainty: Type A from statistics of repeated readings, Type B from other information.

Type A and Type B Uncertainty Explained

Type A uses the standard deviation of repeated measurements. Type B uses certificates, specifications, resolution and experience, with an assumed distribution.

Both are converted to standard uncertainties and combined the same way.

Type A and Type B Uncertainty Formula

Type A: u = s ÷ √n Type B (rectangular): u = a ÷ √3

s	standard deviation
n	number of readings
a	half width of the limits

Example: Display resolution 0.01 bar: a = 0.005, u ≈ 0.0029 bar.

Calculators for Type A and Type B Uncertainty

CalculatorMeasurement Uncertainty CalculatorFree online calculator with formula and worked example.CalculatorRepeatability CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadMeasurement Uncertainty Budget Excel SheetFree download in Excel and PDF.

Frequently Asked Questions

What are Type A and Type B Uncertainty?

Type A and Type B uncertainty are the two ways of evaluating uncertainty: Type A from statistics of repeated readings, Type B from other information.

Is Type B less reliable?

No, it is just evaluated differently; both are valid.

When is a normal distribution used for Type B?

For values from certificates stated with a coverage factor; divide by that k.

Learn more on the blog

Calibration traceability: 6 proven links for trusted results

A practical guide on instrumentationblog.in with more detail on type A and type B uncertainty and how it is applied on real plants.

Read Full Article

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