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Re: st: calculate probability for clogit
From
Steve Samuels <[email protected]>
To
[email protected]
Subject
Re: st: calculate probability for clogit
Date
Tue, 20 Apr 2010 16:12:44 -0400
I know almost nothing about discrete choice experiments, so please
read the following comments with that in mind.
1. -asclogit- might be a better choice than -clogit-, as it will more
easily include person-level variables like gender, income, and sex.
2. Your setup does not identify the individual in any way. The
examples for -asclogit- and -clogit- all use the individual as the
case or group variable. As "set" has only four levels, perhaps you can
include it as a person-level variable.
3. The examples in -asclogit- consider alternatives based on one
attribute (factor). You have three factors and these generate 12 (=
3 x 2 x 2) possible options, with 66 possible pairwise comparisons.
You selected 32 of these, divided into four sets. I'm curious--is
there a reference for this experimental design? Is the choice of
comparisons and construction of the sets optimal or balanced in some
sense?
4. For predicted probabilities, use the -pr- option in -asclogit- .
Steve
On Tue, Apr 20, 2010 at 9:39 AM, Patty_FARE_Guelph Apichaya
<[email protected]> wrote:
> Hi all,
>
> I use STATA to analyze discrete choihce experiment. My choice design has 32 choice sets with each 2 options (A and B). Each option include 3 factors: price (13,15,17), brand (AA,BB), labeling (animal,plant). The choice set will look like this.
> Option A OptionB
> price 13 15
> brand AA BB
> labeling animal plant
>
> From 32 choice sets is divide into 4 block with each 8 choice sets. Each individual (100 individuals) get 1 block (8 choice sets) and ask to choose between option A or B.
>
> choice = 1 chosen option, 0 not chosen option
> set = same for two alternatives for each set i.e. there are 32 choice sets, it is repeated number from 1 to 32 and start it
> again for the next 32 choice sets.
>
> This is the code; clogit choice price brand labeling, group(set)
>
> I also want to include individual characteristics; gender, income, age. how I can do it?
>
> How I can calculate the probability from people choosing choice?
>
> Any suggestion would be great.
> Pat
>
>
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--
Steven Samuels
[email protected]
18 Cantine's Island
Saugerties NY 12477
USA
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Fax: 206-202-4783
*
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