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RE: st: RE: How to find Max value.


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: How to find Max value.
Date   Sat, 19 Jun 2004 20:22:42 +0100

Thank you for the further detail. However, 
if I understand correctly, you are asking a 
very strange question here. Since -mf- 
(presumably -rf- is the same thing or similar) 
is measured to 1 or 2 decimal 
places, the maximum is quite likely to be unique 
for each subset (time and temperature), and the percent equal to the 
maximum will just be 100 / number in subset. 
Fortuitously, you may get tied values, but 
it is difficult to believe that their frequency 
would reflect properties of statistical 
or scientific interest. In addition, if you attempt 
to count how many values are equal to the maximum, 
you are likely to run into the precision problems 
detailed at [U] 16.10. 

Providing Stata code would just be giving 
you the means of doing something bizarre, 
I believe. 

Nick 
n.j.cox@durham.ac.uk 

Syed O Masood
 
> I have put a piece of data below. 
> I need to find what percent of people have maximum
> value in the variable rf at time 1 and temp 26, what
> percent of people will have maximum value of mf at
> time 2 and temp 26, what percent of people have max
> value of mf at time 3 and temp 26 and similarly for
> tmep 35oC. 
> 
> Thanks in advance for your help & support
>  
> . list temp time mf
> 
>      +---------------------+
>      | temp   time      mf |
>      |---------------------|
>   1. |   26      1     5.5 |
>   2. |   26      2    8.64 |
>   3. |   26      3   12.03 |
>   4. |   35      1    8.64 |
>   5. |   35      2    5.59 |
>      |---------------------|
>   6. |   35      3    9.02 |
>   7. |   26      1    3.88 |
>   8. |   26      2    8.63 |
>   9. |   26      3   10.35 |
>  10. |   35      1    8.34 |
>      |---------------------|
>  11. |   35      2   10.22 |
>  12. |   35      3   11.25 |
>  13. |   26      1    3.29 |
>  14. |   26      2    6.12 |
>  15. |   26      3    7.37 |
>      |---------------------|
> 
> --- Nick Cox <n.j.cox@durham.ac.uk> wrote:
> > This isn't very clear to me. What percent 
> > of anything is equal to the maximum value 
> > is very sensitive to the resolution of measurement, 
> > and as such doesn't seem a very obvious 
> > thing to calculate. 
> > 
> > You may get a better answer if you give 
> > an example table showing some data. 
> > 
> > Nick 
> > n.j.cox@durham.ac.uk 

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