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RE: st: converting non-integer weights into integer weights


From   Ramani Gunatilaka <Ramani.Gunatilaka@buseco.monash.edu.au>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: converting non-integer weights into integer weights
Date   Fri, 21 Nov 2003 04:07:55 +0000

Stephen,
Thanks so much for the free tute. I really appreciate it.
Ramani

Stephen P Jenkins <stephenj@essex.ac.uk> wrote:
> > -----Original Message-----
> > From: owner-statalist@hsphsun2.harvard.edu 
> > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of 
> > Ramani Gunatilaka
> > Sent: 20 November 2003 09:32
> > To: statalist@hsphsun2.harvard.edu
> > Subject: RE: st: converting non-integer weights into integer weights
> > 
> > 
> > Stephen,
> > Thanks so much for the feedback. 
> > I didn't think of using aweights because they are defined as 
> > being inversely proportional to the variance of an 
> > observation. The weights in my data represent the total 
> > number of households in the entire population that each 
> > particular household represents - probably derived as some 
> > fraction of the entire population. 
> > The two are not equivalent, are they?
> > That's why I thought of using fweights. I was following 
> > Kieran's suggestion when I got your mail. I'd appreciate your 
> > comments on this, if it is not too much trouble. Ramani
> 
> Regardless of how aweights are sometimes motivated, and how your weights
> are motivated, you've ended with a variable that is the weight that you
> want to use and it is non-integer. Using the aweight option is simply a
> means of doing your calculations.  (Where the different assumptions
> about what underlies the weights really matters typically affects the
> calculation of the sampling variances associated with the statistics of
> interest rather than the point estimates, and it is the latter that you
> seek)
> 
> 
> Stephen
> -------------------------------------------------------------
> Professor Stephen P. Jenkins <stephenj@essex.ac.uk>
> Institute for Social and Economic Research
> University of Essex, Colchester CO4 3SQ, U.K.
> Tel: +44 1206 873374.  Fax: +44 1206 873151.
> http://www.iser.essex.ac.uk   
> 
> 
> > 
> > Stephen P Jenkins <stephenj@essex.ac.uk> wrote:
> > > Why do you need to convert the weights to integers?  The 
> > -_pctile- and
> > > -kdensity- commands accept aweights, and aweights can be 
> > non-integer?
> > > 
> > > 
> > > Stephen
> > > 
> > > > > -----Original Message-----
> > > > > From: owner-statalist@hsphsun2.harvard.edu
> > > > > [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Ramani
> > > > > Gunatilaka
> > > > > Sent: Thursday, 20 November 2003 10:42 AM
> > > > > To: statalist@hsphsun2.harvard.edu
> > > > > Subject: Re: st: converting non-integer weights into 
> > integer weights
> > > > >
> > > > >
> > > > > Hi all,
> > > > > I am sorry to bug you with this problem again but the solution 
> > > > > that
> > > > > Branko very kindly suggested didn't work for me. To recap 
> > > > briefly, I
> > > > > need to use weights with the  _pctile and kdensity
> > > > commands. But mine
> > > > > are non-integer weights (for an example see my first mail
> > > > below) and
> > > > > even though I multiplied the weights by 100 as Branko
> > > > suggested (since
> > > > > they have only two decimal places) I get an error as follows:
> > > > >
> > > > >  use c:\data95\hhcons95, clear
> > > > >
> > > > > . keep x hhsize w
> > > > >
> > > > > . gen freq=hhsize*w*100
> > > > >
> > > > > . _pctile x [fweight=freq],
> > > > > percentiles(5,10,15,20,25,30,35,40,45,50,55,60,65,7
> > > > > > 0,75,80,85,90,95,99)
> > > > >
> > > > > may not use noninteger frequency weights
> > > > > r(401);
> > > > >
> > > > > I have a hunch that multiplying the original weight by 100
> > > > made it too
> > > > > long to be stored as an integer. The largest transformed
> > > > weight then
> > > > > becomes 7 digits.
> > > > >
> > > > > Would anybody have any ideas on this?
> > > > >
> > > > > Thanks so much,
> > > > > Ramani
> > > > >
> > > > >
> > > > >
> > > > > Bmilanovic@worldbank.org wrote:
> > > > > >       Ramani,
> > > > > >
> > > > > > why don;t you multiply the weights by a hundred (or 
> > whatever; a
> > > > > > thousand), and then create integers. kdensity should  
> > work then.
> > > > > >
> > > > > >       best, branko
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >    IMPORTANTISSIMO!!!
> > > > > >    From around October 15, 2003 my new
> > > > > >    Email address will be
> > > > > >    bmilanovic@ceip.org
> > > > > >
> > > > > >
> > > > > >    ALL ABOUT INEQUALITY IN THE WORLD (AND MORE!)
> > > > > >    http://www.worldbank.org/research/inequality/
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > Ramani Gunatilaka
> > > > > > <Ramani.Gunatilaka@buseco.mon To:
> > > > > > ash.edu.au> Statalist@Hsphsun2.Harvard.Edu
> > > > > > Sent by: cc:
> > > > > > owner-statalist@hsphsun2.harv Subject: st: Use of Weights
> > > > in Kernel
> > > > > > Density Estimation ard.edu
> > > > > >
> > > > > >
> > > > > > 11/16/2003 09:11 AM
> > > > > > Please respond to statalist
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > Hi all,
> > > > > > I hope there maybe someone out there who may be able 
> > to help me
> > > > > with this
> > > > > > query.
> > > > > > I have a household level data set of roughly 19,000
> > > > households with
> > > > > > the following variables: per capita consumption in rupees (x),
> > > > > > population weights
> > > > > > (w) and household size (hhsize) as in the sample 
> > below (I'm sorry 
> > > > > > the column heads are not aligned).
> > > > > >
> > > > > > x            w           hhsize
> > > > > > 204.4059           176.45            3
> > > > > > 402.0174           119.22            6
> > > > > > 218.7155           51.84             8
> > > > > > 1083.199           1266.73           6
> > > > > > 303.6877           169.54            3
> > > > > >
> > > > > > The weights represent the number of households in the entire
> > > > > > population that each particular household represents.
> > > > > >
> > > > > > I need to estimate the kernel density of the consumption
> > > > > distribution and
> > > > > > have
> > > > > > consulted Stata's kdensity function as well as the
> > > > akdensity module
> > > > > > developed by Van Kerm. Both permit the use of weights,
> > > > but only of
> > > > > > fweights and aweights. But
> > > > > > while the weights in my data set are frequency 
> > weights, they are 
> > > > > > certainly not integers as required by Stata.
> > > > > >
> > > > > > Would someone know how I may get round this problem? I'd
> > > > rather use
> > > > > > the kdensity or akdensity commands and not have to write up a
> > > > > > programme from scratch.
> > > > > >
> > > > > > Thanks so much,
> > > > > > Ramani
> > > > > > *
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> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
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> > > > >
> > > > 
> > > > 
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> > 
> 
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