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Re: st: logistic -- items vs scale


From   Christer.Thrane@hil.no
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: logistic -- items vs scale
Date   Thu, 1 Aug 2002 13:56:01 +0200

Ben Dulong wrote:

Consider the variables:

y=0  or  y=1

x1=0 or x1=1
x2=0 or x2=1
x3=0 or x3=1

xtotal = x1+x2+x3
xtotal is a scale calculated from the items x1,x2,x3.


Which is the better syntax?

logistic y xtotal

or

xi: logistic y i.xtotal


The answer: It depends!

Is it theoretically meaningful to summarize the x variables?  Do they
together form an additive scale/dimension?
Are the x's highly correlated?  The more yes'es to these questions, the
more likely the first syntax is the better? However, the last syntax will
(here) also test whether there is a linear relationship between Y and
xtotal.

Best regards,

Christer

Christer Thrane, dr. polit.
Associate Professor, Sociology
Faculty of Tourism and Applied Social Science
Lillehammer College
Gudbrandsdalsv. 350
2626 Lillehammer, Norway
+ 47 61 28 81 70 (fax)
+ 47 61 28 82 47 (phone, work)
+ 47 61 25 68 44 (phone, home)
+ 47 92 29 54 39 (mobile)
E-mail, work: Christer.Thrane@hil.no
E-mail, home: Christer.Thrane@c2i.net





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