| probability scale on 2D line plot? [message #13812] |
Wed, 09 December 1998 00:00  |
Charlotte DeMott
Messages: 7
Registered: January 1998
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Junior Member |
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Does anyone know how to create a "probability axis" for a
line plot? This is an axis that runs from nearly zero to
nearly 1, that is stretched at each end, such that the
cumulative distribution of a normal population appears as a
straight line.
For anyone familiar with the atmospheric sciences, numerous
examples may be seen in Houze and Cheng, 1977, MWR 106,
964-980.
Thanks,
Charlotte
---
Charlotte A. DeMott
Department of Atmospheric Science
Colorado State University
Fort Collins CO 80523
demott@massif.atmos.colostate.edu
970 491 1487
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| Re: probability scale on 2D line plot? [message #13877 is a reply to message #13812] |
Mon, 14 December 1998 00:00  |
Martin Schultz
Messages: 515
Registered: August 1997
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Senior Member |
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Charlotte DeMott wrote:
> Does anyone know how to create a "probability axis" for a
> line plot? This is an axis that runs from nearly zero to
> nearly 1, that is stretched at each end, such that the
> cumulative distribution of a normal population appears as a
> straight line.
>
> For anyone familiar with the atmospheric sciences, numerous
> examples may be seen in Houze and Cheng, 1977, MWR 106,
> 964-980.
>
> Thanks,
> Charlotte
>
> ---
> Charlotte A. DeMott
> Department of Atmospheric Science
> Colorado State University
> Fort Collins CO 80523
> demott@massif.atmos.colostate.edu
> 970 491 1487
Please find attached my little QQNORM program. That's the name of that
"deviation from standard probability distribution" function in SPlus. It
will compute the deviation from the expected probability for each data
point.
Hope this helps,
Martin.
--
------------------------------------------------------------ -------
Dr. Martin Schultz
Department for Engineering&Applied Sciences, Harvard University
109 Pierce Hall, 29 Oxford St., Cambridge, MA-02138, USA
phone: (617)-496-8318
fax : (617)-495-4551
e-mail: mgs@io.harvard.edu
Internet-homepage: http://www-as.harvard.edu/people/staff/mgs/
------------------------------------------------------------ -------
function qqnorm,data
; mgs, 12/14/98, extracted from w_calc.pro
; procedure: sort the data, assign actual "probability" and calculate
; the expected deviation from the mean
; compute mean and standard deviation
bla = moment(data)
mean = bla[0]
sigma = sqrt(bla[1])
; make working copy to store result and compute sort index
tmp = data
tmpind = sort(tmp)
N = n_elements(tmp)
for i=0,n-1 do tmp[tmpind[i]] = gauss_cvf( 1.-(i+0.5)/N )
return,tmp
end
-
Attachment: qqnorm.pro
(Size: 0.47KB, Downloaded 68 times)
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