Hi,
In response to your question regarding dummy vars in multiple linear regression:
Dummy variables are useful because they enable us to use a single regression equation to represent multiple groups. This means that we don't need to write out separate equation models for each subgroup. The dummy variables act like 'switches' that turn various parameters on and off in an equation.
For more info here is a great link:
http://trochim.human.cornell.edu/kb/dummyvar.htm
Regards,
-cdb
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Christopher D. Birtch
Salient Research Labs, Inc.
The University of Western Ontario
RESEARCH PARK
100 Collip Circle, Suite 100
London Ontario Canada N6G 4X8
Phone: 519-858-5140 ext:25090
FAX : 519-858-5048
---------- Original Message ----------------------------------
From: Dr A Coomarasamy <[log in to unmask]>
Reply-To: Dr A Coomarasamy <[log in to unmask]>
Date: Mon, 12 Mar 2001 21:02:03 -0800
>could someone please explain the logic behind using 'dummy variables' in multiple linear regression where there is a catergorical variable with three or more categories? why is this done?
>
>cheers
>
>-----------------------------------------
>A Coomarasamy
>Tel 0956 498 457
>[log in to unmask]
>-----------------------------------------
>
>
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