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st: RE: how to manipulate the r(centiles) macro


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: how to manipulate the r(centiles) macro
Date   Thu, 8 Aug 2002 17:05:20 +0100

Radu Ban

> I have computed a lot of centiles (44 to be more exact) for 
> a variable and I
> was wondering if there is a quick way to recall the 
> requested centiles.
> I know the requested centiles are stored in a
> macro - r(centiles) but I don't know how to recall them separately.

The documentation on this -- I take it Radu is referring to 
-centile- -- is terse and to see what is going on you need to issue 

. return list 

after a -centile- command. 

r(centiles) just echoes what you asked for in the -centile()- 
option. The values of the centiles are in r(c_1), r(c_2), etc. 

This example shows some techniques which may be pertinent. 

. qui centile mpg, c(5 10 25 50 75 90 95) 

. ret li

scalars:
            r(n_cent) =  7
                 r(N) =  74
              r(ub_7) =  40.82632136492616
              r(lb_7) =  28.68068344901154
               r(c_7) =  34.25
              r(ub_6) =  34.79482196757711
              r(lb_6) =  26
               r(c_6) =  29.5
              r(ub_5) =  26.07109169597815
              r(lb_5) =  22.43244200253517
               r(c_5) =  25
              r(ub_4) =  22
              r(lb_4) =  19
               r(c_4) =  20
              r(ub_3) =  18
              r(lb_3) =  16
               r(c_3) =  17.75
              r(ub_2) =  16
              r(lb_2) =  14
               r(c_2) =  14
              r(ub_1) =  14.31931655098844
              r(lb_1) =  12
               r(c_1) =  14

macros:
          r(centiles) : "5 10 25 50 75 90 95"

.  tokenize `r(centiles)' 

. local nc : word count `r(centiles)' 

. forval i = 1 / `nc' { 
  2. di "centile `i'  (``i'' percentile) is " r(c_`i') } 

centile 1  (5 percentile) is 14
centile 2  (10 percentile) is 14
centile 3  (25 percentile) is 17.75
centile 4  (50 percentile) is 20
centile 5  (75 percentile) is 25
centile 6  (90 percentile) is 29.5
centile 7  (95 percentile) is 34.25

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

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