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Re: st: Removing a panel observation if it does not have an entry for a certain period
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: Removing a panel observation if it does not have an entry for a certain period
Date
Wed, 8 Jan 2014 01:19:49 +0000
Should be
drop if present30 == 0
Nick
[email protected]
On 8 January 2014 01:19, Nick Cox <[email protected]> wrote:
> <>
>
> bysort cert : egen present30 = total(period == 30)
> drop if cert == 0
> drop present30
>
> See also http://www.stata-journal.com/article.html?article=dm0055
>
> Nick
> [email protected]
>
> On 8 January 2014 00:48, Travis Cyronek <[email protected]> wrote:
>
>> I am using an unbalanced panel with a total
>> of about 450000 observations. These observations are of roughly 16000
>> banks over 44 quarters. My panel variable is cert (FDIC certification
>> number, assigned to banks with FDI) and my time variable is period (1 for
>> the first quarter in my study, and 44 for the last quarter in my study).
>>
>> I am looking at the effect of a piece of legislation passed during this
>> time frame using a dummy variable. However, the data I have include banks
>> that exited the market before this change and also includes banks that
>> entered the market after. I would like to remove the banks that do not have
>> observations for the period when the legislation was passed (for example,
>> say period 30).
>>
>> All that I have found as far as removing variables involves removing
>> individual observations. I, however, would like to remove the entire set of
>> observations for bank i IF it does not have an observation for period 30.
>>
>> Given that my data file is huge, manually going through each of the 16000
>> banks to see if there is an entry for period 30 is not practical. So I
>> was wondering how I would go about this.
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