# RE: st: composite index

 From "Joon G. Park" To "'statalist@hsphsun2.harvard.edu'" Subject RE: st: composite index Date Fri, 17 Nov 2006 01:07:15 -0600

```Dr. Williams,

Thanks for the quick feedback.
At this point, I think the use of z-scores may the best option. Thanks,
again.

Joon.

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Richard Williams
Sent: Thursday, November 16, 2006 9:13 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: composite index

At 08:39 PM 11/16/2006, Joon G. Park wrote:
>Hi,
>
>I have a quick question on creating a composite index. I've searched
>for this topic on Stata listserv, but without success.
>
>But, anyways, here is my situation:
>
>I have the following three variables:
>
>Variable "A" (Scale: millions; range: from hundreds of thousands to
>millions; Unit: dollar)
>
>Variable "B" (Scale: hundreds; Range: from single digits to three
>double digits; Unit: "size")
>
>Variable "C" (Scale: hundreds; Range: from less than ten to tens of
>thousands; Unit: personnel)
>
>
>I would like to have equal weights attached for each variable that
>will comprise the composite index (I may use weighted index later
>on, depending on how my theory works out). This would seem
>accomplished easily enough via "generate" command with relevant math
syntax.

I guess the question is, why would you think that equal weights are
appropriate, given how different the scales are?  You could do
rescalings, but if you do that that is the same as using different
weights.  It seems like a factor analysis makes as much sense as
anything, assuming you even want to create a scale in the first
place.  Or, maybe create z-scores from the 3 variables and add them
together.

-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
FAX:    (574)288-4373
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EMAIL:  Richard.A.Williams.5@ND.Edu
WWW (personal):    http://www.nd.edu/~rwilliam
WWW (department):    http://www.nd.edu/~soc

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