[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"?


Prof. (FH) PD Dr. Thomas Haslwanter
School of Applied Health and Social Sciences
University of Applied Sciences Upper Austria
FH OÖ Studienbetriebs GmbH
Garnisonstraße 21
4020 Linz/Austria
Tel.: +43 (0)5 0804 -52170
Fax: +43 (0)5 0804 -52171
E-Mail: Thomas.Haslwanter at fh-linz.at<mailto:Thomas.Haslwanter at fh-linz.at>
Web: me-research.fh-linz.at<http://work.thaslwanter.at>
or work.thaslwanter.at

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