Re: varu and stdu

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Re: varu and stdu

Pierre GM-2
Anne, Travis,
I have no problem to get rid of varu and stdu in MaskedArray: they were
introduced for my own convenience, and they're indeed outdated with the
introduction of the ddof parameters. I'll get rid of them next time I post
something on the SVN.

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Re: varu and stdu

Kevin Jacobs <jacobs@bioinformed.com>
I know I'm off topic and maybe a day late, but I'm pained by the naming of ddof. 

It is simply not intuitive for anyone other than the person who thought it up (and from my recollection, maybe not even for him).    For one, most stats folk use 'df' as the abbreviation for 'degrees of freedom'.  Secondly, the we tend to think of the constant bias adjustment as an ~adjustment~ of the sample size or df.  So 'df_adjust=0' or 'sample_adjust=0' will resonate much more.

The other issue is to clearly describe if 'N-1' is obtained by setting the adjustment (whatever it is called) to +1 or -1.  There is a reason why most stats packages have different functions or take a parameter to indicate 'sample' versus 'population' variance calculation.  Though don't take this as a recommendation to use var and varu -- rather I'm merely pointing out that var(X, vardef='sample') is an option (using SAS's PROC MEANS parameter name as an arbitrary example).

In the extremely rare cases I need any other denominator, I'm fine with multiplying by var(x)*n/(n-adjust).

-Kevin


On Mon, Apr 7, 2008 at 9:41 AM, Pierre GM <[hidden email]> wrote:
Anne, Travis,
I have no problem to get rid of varu and stdu in MaskedArray: they were
introduced for my own convenience, and they're indeed outdated with the
introduction of the ddof parameters. I'll get rid of them next time I post
something on the SVN.

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Numpy-discussion mailing list
[hidden email]
http://projects.scipy.org/mailman/listinfo/numpy-discussion


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