[Numpy-discussion] Standard Deviation (std): Suggested change for "ddof" default value

Haslwanter Thomas Thomas.Haslwanter at fh-linz.at
Tue Apr 1 14:27:01 EDT 2014


While most other Python applications (scipy, pandas) use for the calculation of the standard deviation the default "ddof=1" (i.e. they calculate the sample standard deviation), the Numpy implementation uses the default "ddof=0".
Personally I cannot think of many applications where it would be desired to calculate the standard deviation with ddof=0. In addition, I feel that there should be consistency between standard modules such as numpy, scipy, and pandas.

I am wondering if there is a good reason to stick to "ddof=0" as the default for "std", or if others would agree with my suggestion to change the default to "ddof=1"?

Thomas

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Prof. (FH) PD Dr. Thomas Haslwanter
School of Applied Health and Social Sciences
University of Applied Sciences Upper Austria
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or work.thaslwanter.at

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