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Re: compute quartiles of a distribution [message #77914 is a reply to message #77912]

Tue, 18 October 2011 09:36

Thibault Garel
Messages: 55
Registered: October 2009

Member

:) On this one, I am my own reviewer !
I know what I ask sounds weird but that is really what I'd like to
compute. As I want to work with the means, not medians, "statistically
justifiable real" quartiles do not really help. In my case, means and
median may be quite different so that normal 75% quartiles may be out
of the sample...
I am gonna try to find a way to code that.
Thanks again,

Cheers
bing

> bing999 writes:
>> The procedures in summary.pro and cgBoxPlot.pro compute "real"
>> quartiles. Actually, I should not have used this word in my case i
>> guess.
>
>> What I want is the interval [M-Q;M+Q] which encompass 75% of the
>> values of the sample around the mean (not the median) value M, where Q
>> is unique (i.e the same at lower and higher values around M). I do not
>> want the 37.5% above M and the 37.5% below. It makes a little
>> difference with what is calculated with your routines.
>> The idea would be to span the sample starting from the mean, and
>> counting the points at lower and higher values around the mean in an
>> iterative manner, until I have counted 75% of sample. This would give
>> the value of Q at which the 75% is reached. I have a crude idea to do
>> that with for loops but it will take forever...
>
> I'm guessing you are going to have a hard time
> explaining to your reviewers why your "fake"
> quartiles are better than the statistically
> justifiable real quartiles. :-)
>
> Cheers,
>
> David
>
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.idlcoyote.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: compute quartiles of a distribution By: Jeremy Bailin on Tue, 18 October 2011 21:32
		Re: compute quartiles of a distribution By: Jeremy Bailin on Tue, 18 October 2011 12:48
		Re: compute quartiles of a distribution By: Brian Wolven on Tue, 18 October 2011 10:38
		Re: compute quartiles of a distribution By: Thibault Garel on Tue, 18 October 2011 09:36
		Re: compute quartiles of a distribution By: David Fanning on Tue, 18 October 2011 09:25
		Re: compute quartiles of a distribution By: Thibault Garel on Tue, 18 October 2011 09:12
		Re: compute quartiles of a distribution By: Thibault Garel on Tue, 18 October 2011 09:13
		Re: compute quartiles of a distribution By: David Fanning on Mon, 17 October 2011 18:26
		Re: compute quartiles of a distribution By: Vincent Sarago on Mon, 17 October 2011 06:05

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