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Re: st: reshaping data?


From   Yuval Arbel <yuval.arbel@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: reshaping data?
Date   Thu, 25 Oct 2012 16:19:19 +0200

Before going any further, please note that the model you proposed is
incorrectly specified. Any decent Econometric textbook will
demonstrate the endogeneity between P1 and Q1. Moreover, if you would
like to estimate the demand for each product - you need to have some
measure to the level of income of each consumer

On Thu, Oct 25, 2012 at 4:08 PM,  <agostino@unical.it> wrote:
> Dear all,
> I would be grateful if you could help me to address the following problem:
> I have to estimate the equation
>
> Q1=a+b1P1+b2P2+…bnPn+e
>
> Where Q1 is the quantity of item 1 sold by a supermarket during a week , P1
> is the price of item 1 in that week, the other prices are those of the n
> items belonging to the same family of items. My data set is organized as
> follows:
>
>
> Code_item       week    Q       P       Code_family
> 789             1       8       2       1
> 790             1       25      4       1
> 791             1       9       1.3     1
>
> 792             1       12      2       1
>
> 800             1       7       2       2
> 801             1       20      1.2     2
> 802             1       11      1.6     2
>
> 803             1       12      2       2
>
> And so forth for the other weeks and families…
>
> For each item, how can I include in my regression the prices of the other
> (n-1) items of the same family, ignoring the prices of the items belonging
> to other families?
> Thank you in advance
> Maria
>
>
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-- 
Dr. Yuval Arbel
School of Business
Carmel Academic Center
4 Shaar Palmer Street,
Haifa 33031, Israel
e-mail1: yuval.arbel@carmel.ac.il
e-mail2: yuval.arbel@gmail.com

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