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Re: st: creating composite measures


From   Ronan Conroy <rconroy@rcsi.ie>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: creating composite measures
Date   Fri, 23 Aug 2002 10:17:07 +0100

on 22/8/02 7:54 PM, Seth D. Hannah at hannah@fas.harvard.edu wrote:

> What I want to do is combine these four variables into one measure of
> prejudice, which will become a dependent variable in some of my models.
> 
> The only way I could think to do it was to create a new variable prejblk
> with numerical values 1 through 7 that equal the sums of the respective
> 1 through 7's
> from my four variables...

You are making a small scale of prejudice. Have a look at -alpha-. It will
A) check that the variables add up to a reliable scale (invoke the -detail-
option for some very useful information on the individual items)
B) make a composite score by adding up the items and scaling to the original
1-7 metric by dividing by the number of items
C) -alpha- will also recognise items that should be reverse scored and
reverse them unless you tell it otherwise.

Note that items with very poor correlations with the remainder of the scale
will not be recognised as needing reverse scoring, and in this case you
really need to drop the item and rerun -alpha-.

Ronan M Conroy (rconroy@rcsi.ie)
Lecturer in Biostatistics
Royal College of Surgeons
Dublin 2, Ireland
+353 1 402 2431 (fax 2329)

--------------------
And now, Mr President, how about the global alliance against climate change?
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