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Re: st: Creating a dummy variable under certain conditions


From   Abhimanyu Arora <abhimanyu.arora1987@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Creating a dummy variable under certain conditions
Date   Sat, 2 Jun 2012 16:34:41 +0200

Sebas,
Adding to Nick's comment, did you not -xtset- the data? You also have
an option of bys id_var: command, otherwise


On Sat, Jun 2, 2012 at 4:29 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> You will probably want to exclude or ignore the first few observations
> in each panel or -replace- it with missing. Otherwise, what's wrong?
>
> Abhimanyu's slip has already been corrected in this thread, as below.
>
> Nick
>
> On Sat, Jun 2, 2012 at 3:12 PM, sebas nicaise <sebasnicaise@hotmail.com> wrote:
>
>> Thank you for the quick replys.
>>
>>  However, the suggested solutions did not give the right answer.
>>
>> Nick, your solution gives me way too many 1's. I do think the first step with the cusum was the right way to go.
>>
>>  Abhimanyu, your solution does not distinquish between the id's, the calculation has to start over for every gvkey.
>>
>>
>>  Hope you can have another look at it, I will also try to work with the suggestions you gave me.
>>
>>> From: abhimanyu.arora1987@gmail.com
>>> To: statalist@hsphsun2.harvard.edu
>>>
>>> Thanks Nick, yes.
>>> But I would go for your solution which would be better in case he had
>>> a longer lag.
>>>
>>> On Sat, Jun 2, 2012 at 2:56 PM, Nick Cox <njcoxstata@gmail.com> wrote:
>>> > This looks OK as long as you substitute -viol- for -gvkey-. The
>>> > previous values concerned are for -viol-, not -gvkey-.
>>> >
>>> > Nick
>>> >
>>> > On Sat, Jun 2, 2012 at 1:51 PM, Abhimanyu Arora
>>> > <abhimanyu.arora1987@gmail.com> wrote:
>>> >
>>> >> Try this if your data is -xtset-ted
>>> >> gen new_viol_dummy=L.gvkey+L2.gvkey+L3.gvkey+L4.gvkey==0
>>> >
>>> >> On Sat, Jun 2, 2012 at 2:06 PM, sebas nicaise <sebasnicaise@hotmail.com>
>>> >>
>>> >>> I am struggeling with creating a new dummy variable. I have a very large
>>> >>> (unbalanced) panel dataset that looks like this:
>>> >>>
>>> >>>
>>> >>>
>>> >>> date gvkey viol
>>> >>> 1997q1 1021 0
>>> >>> 1997q2 1021 0
>>> >>> 1997q3 1021 0
>>> >>> 1997q4 1021 0
>>> >>> 1998q1 1021 1
>>> >>> 1998q2 1021 0
>>> >>> 1998q3 1021 0
>>> >>> 1998q4 1021 1
>>> >>> 1999q1 1021 0
>>> >>>
>>> >>> 1999q2 1021 0
>>> >>>
>>> >>> 1999q3 1021 0
>>> >>> 1999q2 1023 0
>>> >>> 1999q3 1023 1
>>> >>> 1999q4 1023 0
>>> >>> 2000q1 1023 0
>>> >>> 2000q2 1023 1
>>> >>>
>>> >>>
>>> >>> Where date is calender quarter, gvkey is the company identifier and viol a
>>> >>> dummy which equals 1 if the firm is in violation of a covenant in a private
>>> >>> debt contract.
>>> >>>
>>> >>>
>>> >>>
>>> >>> The problem is that I have to create a new dummy variable ( new violation)
>>> >>> which meets certain conditions.
>>> >>>
>>> >>> The new violation dummy is only allowed to be 1 if in the previous 4
>>> >>> quarters of a certain company (gvkey) is 0.
>>> >>>
>>> >>>
>>> >>>
>>> >>> This means for example that:
>>> >>>
>>> >>>
>>> >>>
>>> >>> date gvkey viol Newviolation
>>> >>> 1997q1 1021 0 0
>>> >>> 1997q2 1021 0 0
>>> >>> 1997q3 1021 0 0
>>> >>> 1997q4 1021 0 0
>>> >>> 1998q1 1021 1 1
>>> >>> 1998q2 1021 0 0
>>> >>> 1998q3 1021 0 0
>>> >>> 1998q4 1021 1 0
>>> >>> 1999q1 1021 0 0
>>> >>>
>>> >>> 1999q2 1021 0 0
>>> >>>
>>> >>> 1999q3 1021 0 0
>>> >>> 1999q2 1023 0 0
>>> >>> 1999q3 1023 1 0
>>> >>> 1999q4 1023 0 0
>>> >>> 2000q1 1023 0 0
>>> >>> 2000q2 1023 1 0
>>> >>>
>>> >>>
>>> >>>
>>> >>> I do not know how to tell Stata to create this variable, Hope someone is
>>> >>> so kind to help me.
>>> >
>>> > *
>>> > * 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/
>>>
>>> *
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>>> * http://www.ats.ucla.edu/stat/stata/
>> *
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>
> *
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