**From:** Achim Zeileis (*zeileis@ci.tuwien.ac.at*)

**Date:** Tue 11 Mar 2003 - 04:03:50 EST

**Next message:**Scot W McNary: "[R] graphics backgrounds from gray to white in png()"**Previous message:**Remko Duursma: "RE: [R] Moving average"**In reply to:**Carlos Ortega: "RE: [R] sampling and gini index"

Message-id: <200303101703.h2AH3on3001479@thorin.ci.tuwien.ac.at>

On Monday 10 March 2003 16:34, Carlos Ortega wrote:

*> Cesar,
*

*>
*

*> For the first part, please check the function included. For the
*

*> sampling, please check "?sample".
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*>
*

*> Regards,
*

*> Carlos.
*

*>
*

*> g.index<-function(y) {
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*> sum.res<-0
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*> y.lg<-length(y)
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*> y.mean<-mean(y)
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*>
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*> for (i in 1:y.lg) {
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*> for (j in 1:y.lg) {
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*> ratio.res<-abs(y[i]-y[j]) / (2 * y.lg^2 * y.mean)
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*> sum.res<-sum.res+ratio.res
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*> }
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*> }
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*> return(sum.res)
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*> }
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*>
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*> y<-rnorm(284)
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*> g.index(y)
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*>
*

A more efficient implementation of the Gini index can be found in the

ineq package. See

help(Gini)

help(ineq)

Z

*>
*

*>
*

*>
*

*> -----Mensaje original-----
*

*> De: r-help-bounces@stat.math.ethz.ch
*

*> [mailto:r-help-bounces@stat.math.ethz.ch]En nombre de Cesar Ortega
*

*> Enviado el: lunes, 10 de marzo de 2003 12:17
*

*> Para: r-help@stat.math.ethz.ch
*

*> CC: r-help@stat.math.ethz.ch
*

*> Asunto: [R] sampling and gini index
*

*>
*

*>
*

*> Hi there,
*

*>
*

*>
*

*> I am new in R, and I was wondering if I could do the following in R,
*

*> since I have tried in SPSS and I have only done part of it. I
*

*> would appreciate any help to build this routine in R, if possible:
*

*>
*

*>
*

*>
*

*> I have a column of 284 elements Y, [...]
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*>
*

*> > Iam reading these as 284 cases with a single
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*> > variable, which I will call Y
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*> >
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*> > > where first I need to calculate:
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*> > >
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*> > >GINP=[SUMi SUMj {|Yi - Yj|}]/[2(N**2)*MEAN(Y)], where Yi and Yj
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*> >
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*> > are
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*> >
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*> > >the 284 elements, 0<Y1<=Y2...<=Y284. j: is the next position of
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*> > > i.
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*> >
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*> > Here, I am doing a calculation to yield a single number.
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*> > Calculating
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*>
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*> (I assume that N=284)
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*>
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*> > >Next, I need to take the 284 numbers and resampling them in
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*> >
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*> > [groups
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*> >
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*> > >of] n data (like 3, 4, 5, etc) for M number of samples ( like
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*> >
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*> > 1000,
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*> >
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*> > >2000, etc, one at a time) in 3 sampling methods:
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*> > >
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*> > >1. Simple sampling without replacing.
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*> > >2. Fixed systematic sampling.
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*> > >3. Proportional sampling Madow.
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*>
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*> SIMPLE SAMPLING WITHOUT REPLACING THE POSITION VALUE, FOR INTANCE 3,
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*> IF WE HAVE THE POSITION 3,7,9 WITH ITS VALUES, WE COULD HAVE 3,7,10,
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*> BUT WE COULD NOT HAVE THE POSITIONS 9,3,7 AGAIN. SO THIS IS A
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*> COMBINATION, AND IF WE TAKE 3 COMBINATIONS OUT 284 WE HAVE
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*> 284!/(3!*281!). AND WE NEED TO START FROM 1000 GROUPS OF
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*> COMBINATIONS. IT IS LIKE
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*> IF WE HAVE 1,2,3,4,5 AND WE WANT COMBINATIONS OF 2, WE COULD HAVE IN
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*> 1,2 AND 1,3 AND 1,4 AND 1,5 AND 2,3 AND 2,4, ETC, BUT IN RANDOM
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*> ORDER.
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*>
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*> > >After I have the M(1000, 2000) samples of n ( 3,4, 5)elements in
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*> >
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*> > a column,
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*> >
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*> > >I need to take one by one each of the 1000 samples of each n
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*> >
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*> > elements
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*> >
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*> > >and calculate:
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*> > >
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*> > >PI(i)=n/N in simple and fixed sampling and i belogns to the
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*> >
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*> > sample. In
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*> >
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*> > >MADOW PI(i) is proprortional to an auxiliary variable Xi:PI(i)=
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*> >
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*> > RXi,
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*> >
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*> > >where r= MOD(TN,R), and TN=SUMi(Xi), i to N.
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*>
*

*> WE KNOW r, AND TN, BUT WE NEED TO FIND R FROM THE MODAL AND r.
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*>
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*> AND CALCULATE:
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*> > >ESTIMATED N= SUM {1/PI(i)};
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*> > >ESTIMATED T(Y)= SUM {Yi/PI(i)}; i belongs to the sample.
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*>
*

*> GINMi=[SUMi{(Yi/PI(i))*[1/PI(i)+SUMj(2/PI(j)]}]/[(2*ESTIMATED
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*> N*ESTIMATED T)]. i belongs to M (1000) times, WHERE j=i+1
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*>
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*> WE HAVE ONLY ONE VARIABLE Y, BUT WITH THE FIRST POSITION i AND THE
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*> NEXT j, IN THE ASCENDING ORDER.
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*>
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*> > >And last to get the errors as:
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*> > >
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*> > >E1= [SUMi {|GINP-GINMi |}]/[M] ; i belongs M
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*> > >
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*> > >E2= SQRT[SUMi {|GINP-GINMi |}]/[M]; i belongs TO M
*

*>
*

*> ______________________________________________
*

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*

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**Next message:**Scot W McNary: "[R] graphics backgrounds from gray to white in png()"**Previous message:**Remko Duursma: "RE: [R] Moving average"**In reply to:**Carlos Ortega: "RE: [R] sampling and gini index"

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