2. Which uncertainty assessment method should be used?

Although various possibilities exist, the best-known and most widely used method is the one developed in the GUM. This method is assumed to be familiar to the reader. However, we'll give you a brief overview.

• The first step is to analyze and understand the measurement process.

• The next step is to draw up a list of the parameters that may influence the measurement result. For this, we recommend using the 5M diagram described in the next step.

• For each variable that can influence the measurement result, the elementary standard deviation must be evaluated. This standard deviation can be determined statistically by repeating the measurement a large number of times (type A method). It can also be determined from documented information (type B method).

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