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Re: st: DiD
From
inggrid <[email protected]>
To
[email protected]
Subject
Re: st: DiD
Date
Wed, 30 Mar 2011 01:39:18 +0800 (SGT)
Dear Federico,
I have changed the variable of treat. As your suggestion, by ignoring year, I give a value of 1 to the individuals with the same id (2000 and 2007). But, STATA still dropped my interaction variable. Indeed, my data sets are unbalanced panel with a larger sample in 2007.
id year y program treat post05 treat_post05
1 2000 10 0 0 0 0
2 2000 20 0 0 0 0
3 2000 30 0 0 0 0
4 2000 40 0 1 0 0
5 2000 50 0 1 0 0
6 2000 60 0 1 0 0
1 2007 70 0 0 1 0
2 2007 80 0 0 1 0
3 2007 90 0 0 1 0
4 2007 100 1 1 1 1
5 2007 110 1 1 1 1
6 2007 120 1 1 1 1
7 2007 130 0 0 1 0
8 2007 140 0 0 1 0
9 2007 150 0 0 1 0
Thanks in advance.
Best regards,
Inggrid
--- On Tue, 3/29/11, [email protected] <[email protected]> wrote:
> From: [email protected] <[email protected]>
> Subject: Re: st: DiD
> To: [email protected]
> Date: Tuesday, March 29, 2011, 10:33 PM
> 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
> > > *
> > > * 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/
> > >
> >
> >
> >
> >
> > *
> > * 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/
>
> *
> * 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/
>
*
* 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/