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Re: st: DiD
From
[email protected]
To
[email protected]
Subject
Re: st: DiD
Date
Tue, 29 Mar 2011 17:33:31 +0200
I see many problems. First of all, I would expect an identifier, and to find it twice for each value (1 for year 2000 and 1 for year 2007). The only variable that could be an identifier is "y", but it doesn't respect this charachteristic. Then, you have 3 variables that are absolutely identical ("treat", "program" and "treat_post05"). So these commands:
> gen treat=(program!=0)
> gen treat_post05 = treat*post05
are unuseful because they just generate clones of "program", because "program" is always equal to 1 (when different from 0) and is always equal to 0 for year 2000.
Federico
----- Messaggio originale -----
Da: inggrid <[email protected]>
Data: Tuesday, March 29, 2011 17:13
Oggetto: Re: st: DiD
A: [email protected]
> Hello again,
>
> I have found my problem. To clarify everything, I am repeating
> my case. I have a two period panel data, 2000 and 2007. In 2005,
> there was a policy reform. Therefore, I can identify the
> participants by using data from 2007. I name it as
> "program".Then, the treated group is equal to "program". I
> generated treat_post05, an interaction dummy (the treatment
> effect).Consequently, treat_post05=treat.
>
> Here is the example:
> year y program treat post05 treat_post05
> 2000 10 0 0 0 0
> 2000 20 0 0 0 0
> 2000 30 0 0 0 0
> 2000 40 0 0 0 0
> 2000 50 0 0 0 0
> 2000 60 0 0 0 0
> 2007 70 0 0 1 0
> 2007 80 0 0 1 0
> 2007 90 0 0 1 0
> 2007 100 1 1 1 1
> 2007 110 1 1 1 1
> 2007 120 1 1 1 1
>
>
> Basically, I can use the the simple t-test. But, I still need to
> include some control variables.
>
> Any idea how to solve this?
>
> Many thanks beforehand.
>
> Best regards,
> Inggrid
>
>
> --- On Tue, 3/29/11, [email protected]
> <[email protected]> wrote:
>
> > From: [email protected] <[email protected]>
> > Subject: Re: st: DiD
> > To: "inggrid" <[email protected]>
> > Cc: [email protected], [email protected]
> > Date: Tuesday, March 29, 2011, 7:06 PM
> > > gen post05 = year>2000
> > > gen treat_post05 = treat*post05
> >
> > > note: post05 omitted because of collinearity
> > > note: treat_post05 omitted because of collinearity
> >
> > May be "post05" has been omitted because it's always equal
> > to 1, and treat_post05 because it's always equal to "treat".
> > I guess you misspecified the condition of post05 (it
> > shouldn't be "year>2000", but "year>2004" or
> > "year>2005").
> > Federico
> > *
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> >
>
>
>
>
> *
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