[Numpy-discussion] Standard Deviation (std): Suggested change for "ddof" default value
davidmenhur at gmail.com
Fri Apr 4 08:50:08 EDT 2014
On 2 April 2014 16:06, Sturla Molden <sturla.molden at gmail.com> wrote:
> <josef.pktd at gmail.com> wrote:
> > pandas came later and thought ddof=1 is worth more than consistency.
> Pandas is a data analysis package. NumPy is a numerical array package.
> I think ddof=1 is justified for Pandas, for consistency with statistical
> software (SPSS et al.)
> For NumPy, there are many computational tasks where the Bessel correction
> is not wanted, so providing a uncorrected result is the correct thing to
> do. NumPy should be a low-level array library that does very little magic.
All this discussion reminds me of the book "Numerical Recipes":
"if the difference between N and N - 1 ever matters to you, then you
are probably up to no good anyway -- e.g., trying to substantiate a
hypothesis with marginal data."
For any reasonably sized data set, it is a correction in the second
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