Re: weird statistics bug in wp34s Message #3 Posted by Paul Dale on 19 June 2013, 2:02 a.m., in response to message #1 by Andrew Nikitin
For each accumulation you made, the value in Y was unchanged so sy should be zero.
However, the problem is due to a rounding error during the calculation of sy. Sigma y2 - n * (sigma y)2 ends up being slightly negative.
I'd have preferred to use the robust formulas for this but was hamstrung by the need for backwards compatibility.
I've committed a fix which will be in the next firmware revision.
- Pauli
Edited: 19 June 2013, 2:08 a.m.
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