Uncertainty calculation Met Cal vs GUM
An particular way to calculate of uncertainty is available in several guides of expression of uncertainty.
All of them explain like find the type A uncertainties based on a sequence of measurements at a particular test point.
Most of them used the formula:
S1 = (SDEV / Square root(N) ) where:
1. N is the number of measurements
2. SDEV is the standard deviation of the measurements
But in the document this formula have.a new parameter , the F factor
So, the new formula in this document is
S1 = (SDEV / Square root(N) ) * F
F is based on the half the values of Student’s T distribution and the number of
degrees of freedom.
How you know, at the end ,you need to report the expanded uncertainty on based in Student's T again.
So, I think that is like expand the uncertainty twice.
I don't understand very well, what is the reason for this.
Could someone explain the reason?
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