
From  Jeph Herrin <junk@spandrel.net> 
To  statalist@hsphsun2.harvard.edu 
Subject  Re: st: RE: Decile sorts 
Date  Thu, 09 Nov 2006 18:45:49 0500 
Maybe I'm missing something, but why not: foreach X of varlist c1* { xtile deciles=`X', n(10) bys deciles: egen R`X'=mean(`X') } ? hth, Jeph Nick Cox wrote:
Various comments sprinkled here and there. You may have
strong reasons to use these decile bins, but binning strikes me as, usually, at best a means towards an end (or perhaps ends towards some means). Some nonparametric
regression might do more justice to the data.
Also, you are mixing two naming conventions 1...10 and 10...90. Just use one.
Nick n.j.cox@durham.ac.uk
Thomas Erdmann
I am trying to sort my observations into deciles according to one attribute
and afterwards calculating the average of another attribute of those ten groups.Please find the code I came up with below [lines with ... are omitted], yrm is the time variable (YearMonth)
(1) As far as I can tell it works out, but a) it's a lot of code and
b)produces a lot of variables and c)generating the output is rather awkward.
Could you give me hints on how to implement a smarter solution or if there
are any errors in the way the calculation is carried out currently?
This is two loops rolled out into one.*** Generate Percentiles sort yrm foreach X of varlist c1* { by yrm: egen p10_`X'= pctile(`X'), p(10.0) by yrm: egen p20_`X'= pctile(`X'), p(20.0) by yrm: egen p30_`X'= pctile(`X'), p(30.0) ... by yrm: egen p90_`X'= pctile(`X'), p(90.0) }
sort yrm foreach X of varlist c1* { forval i = 10(10)90 { by yrm : egen p`i'_`X' = pctile(`X'), p(`i') }
}
*** Sort into Percentile groupsSimilar story with boundary conditions.
foreach X of varlist c1* {
gen G_`X'=1 if `X'<p10_`X' & `X'~=.
replace G_`X'=2 if `X'>p10_`X' & `X'<p20_`X' ... replace G_`X'=9 if `X'>p80_`X' & `X'<p90_`X' replace G_`X'=10 if `X'>p90_`X' & `X'~=.
}
foreach X of varlist c1* {
gen byte G_`X' = `X' < p10_`X'
forval i = 2/9 { local j = 10 * `i' replace G_`X' = `i' if `X' < p`j'_`X' & G_`X' == 0 }
replace G_`X' = cond(`X' == ., ., 10) if G_`X' == 0 }
Why do you need all these variables? The results for bin are disjoint, so can be put in a single variable.*** Calculate return mean for each group sort yrm foreach X of varlist G* { by yrm: egen R1`X'= mean(c1ds_ri) if `X'==1 by yrm: egen R2`X'= mean(c1ds_ri) if `X'==2 ... by yrm: egen R9`X'= mean(c1ds_ri) if `X'==9 by yrm: egen R10`X'= mean(c1ds_ri) if `X'==10 }
foreach X of varlist G* { bysort yrm `X' : egen R`X' = mean(c1ds_ri)
}
Having said that, it can probably done more directly with a series of collapses.
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