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Re: st: What grouping should I use for clogit?


From   Hadji Cortez Jalotjot <jalotjot@yahoo.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: What grouping should I use for clogit?
Date   Tue, 24 Jan 2012 20:48:33 -0800 (PST)

Hi Klaus!

Thanks for the response.


My experimental design is based on what is described by Bunch (1996). 
A starting design is generated.  I used R to generated an optimal
design.  This starting design served as the first alternative in my choice
experiment.  A foldover of the starting design is the second alternative.
 
Generic attributes were used.

 
My
dataset looks like this (this is for respondent 1):
 
respno - id of each respondent
obsid - same number means it belong to
the same choice set
choice - dummy var YES or No
the rest are the explanatory variables (attributes of a vehicle)


respno obsid choice eng1_GAS eng2_DIE eng3_LPG eng4_HEV eng5_ELE pp1_700K pp2_1M pp3_more1M range1_more450 range2_450 range3_200 c100km1_400 c100km2_600 incentv1_WITH incentv2_NO emis1_same emis2_80 NONE 
1 1 1 0 0 0 0 1 0 1 0 0 1 0 1 0 1 0 0 1 0 
1 1 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 1 1 0 0 
1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 2 1 0 0 0 1 0 1 0 0 1 0 0 1 0 1 0 0 1 0 
1 2 0 0 0 1 0 0 0 0 1 0 0 1 0 1 0 1 1 0 0 
1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 3 1 0 1 0 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 
1 3 0 1 0 0 0 0 0 1 0 0 0 1 0 1 0 1 1 0 0 
1 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 4 1 0 0 1 0 0 0 0 1 1 0 0 0 1 0 1 1 0 0 
1 4 0 0 1 0 0 0 0 1 0 0 0 1 1 0 1 0 0 1 0 
1 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 5 0 0 1 0 0 0 0 1 0 0 0 1 0 1 0 1 0 1 0 
1 5 0 1 0 0 0 0 1 0 0 0 1 0 1 0 1 0 1 0 0 
1 5 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 6 1 0 0 1 0 0 0 1 0 1 0 0 1 0 1 0 0 1 0 
1 6 0 0 1 0 0 0 1 0 0 0 0 1 0 1 0 1 1 0 0 
1 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 7 0 0 0 0 1 0 0 1 0 1 0 0 1 0 0 1 1 0 0 
1 7 1 0 0 1 0 0 1 0 0 0 0 1 0 1 1 0 0 1 0 
1 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 8 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 1 0 0 
1 8 1 0 0 0 0 1 1 0 0 0 1 0 0 1 1 0 0 1 0 
1 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 9 0 1 0 0 0 0 0 0 1 0 1 0 1 0 1 0 1 0 0 
1 9 1 0 0 0 0 1 0 1 0 1 0 0 0 1 0 1 0 1 0 
1 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 
1 10 1 0 0 1 0 0 0 1 0 0 1 0 0 1 1 0 0 1 0 
1 10 0 0 1 0 0 0 1 0 0 1 0 0 1 0 0 1 1 0 0 
1 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 


My dependent variable is choice.
 
I understand clogit analyzes the data by
groups.
 
So which should I assign as group? Each
individual is the group (respno) OR each choice experiment (obsid)?
 
Thanks!
 Hadji




----- Original Message -----
From: Klaus Pforr <kpforr@googlemail.com>
To: statalist@hsphsun2.harvard.edu
Cc: 
Sent: Tuesday, January 24, 2012 8:11 PM
Subject: Re: st: What grouping should I use for clogit?

Dear Hadji,

could tell a little bit more about your data, and the experimental 
design? A data example would be helpful.

best

Klaus

Am 23.01.2012 07:46, schrieb Hadji Cortez Jalotjot:
> I am estimating a choice model using the clogit command.  Data is from a choice experiment.
>
> Each respondent was shown 10 choice sets.  Each choice set has 3 choices.
>
> So basically, each respondent corresponds to 30 rows of observations.
>
> My question is, should the respondents (respno) be my group for the clogit?  or should I treat each choice as the "group"?
>
> Any suggestions or explanations are appreciated.
>
> Hadji
>
>
> *
> *   For searches and help try:
> *  http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/


-- 
__________________________________

Klaus Pforr
MZES AB - A
Universität Mannheim
D - 68131 Mannheim
Tel:  +49-621-181 2797
fax:  +49-621-181 2803
URL:  http://www.mzes.uni-mannheim.de

Besucheranschrift: A5, Raum A309
__________________________________

*
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*
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