DOC: is confusing for ddof parameter of sem, var and std functions

[recontemplator]

pandas/pandas/core/generic.py

Lines 7160 to 7161 in 7bb204a

	ddof : int, default 1
	degrees of freedom

It states that ddof is for degrees of freedom with default value of 1. But actually it is for "Delta degrees-of-freedom" (even the name of the parameter is abbreviation of that definition). The meaning is: how many degrees of freedom to adjust relative to the population size. Default of 1 - means we need to adjust by one, not use one as a value of degrees of freedom (thats makes no sense). All functions are worked as expected, but documentation on ddof parameter is confusing.

[sinhrks]

Yeah it should be fixed according to the latest numpy doc. PR is welcome!

https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.std.html

[jreback]

sure @recontemplator would you like to do a PR

[butterflyskip]

Hi,
Newbie here, would like to take a stab at this.

txs