Activities

Distribution The normal distribution

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Uncertainty calculation in chemical analysis

• Repeated result.
• Used in most of measurements.
• uncertainty is simply mean value divided by the coverage factor.

02/02/2022
Uncertainty calculation in chemical analysis
Distribution Rectangular and triangular distribution

• Rectangular distribution

• triangular distribution

Sources of uncertainty

02/02/2022
Uncertainty calculation in chemical analysis
In practice the uncertainty on the result may arise from many possible sources, examples such as:
- Incomplete definition of the measurand.
- Sampling.
- Matrix effects and interferences.
- Environmental conditions.
- Uncertainties of masses and volumetric equipment.
- Reference values.
- many other sources.

How to obtain the Sources of your uncertainty ?

02/02/2022
Uncertainty calculation in chemical analysis
It is commonly necessary to develop and record a list of sources of uncertainty relevant to an analytical method.
The strategy has two stages:

• Identifying the effects on a result In practice.
• Simplifying and resolving duplication.