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3. The Danger of Including Mistakes

Let’s include a measurement with a mistake and see what happens.

Make the first measurement 46.66, an error of 1.00 units.

num value v=meas=MPV v2
1 46.66 46.66-45.912 = +0.748 0.559504
2 45.66 45.66-45.912 = -0.252 0.063504
3 45.68 45.68-45.912 = -0.232 0.053824
4 46.65 45.65-45.912 = -0.262 0.068644
sums 183.65   0.745476

 

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Note how large the standard deviation and EMPV error become. That’s because both are affected by the huge increase in the residuals caused by pushing parts of the 1.00 unit error into all of them.

Always: get rid of mistakes before trying to analyze random errors.

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