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Re: st: drop variables with missing values
From
San Chu <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: drop variables with missing values
Date
Fri, 27 Jul 2012 03:26:03 -0700 (PDT)
Hi Philipp,
Please try this:
sort ID Time
by ID : gen gap = 0
by ID : replace gap = 1 if (_n>1) & missing(Return) & !missing(Return[_n-1])
by ID : egen de l= max(gap)
drop if del == 1
drop gap del
Best regards,
San
________________________________
From: "Braunfels, Philipp (Stud. SBE / Alumni)" <[email protected]>
To: "[email protected]" <[email protected]>
Sent: Thursday, July 26, 2012 2:42 PM
Subject: Re: st: drop variables with missing values
In addition to my last mail:
maybe it is helpful to visualize the "delete gap" problem (I want to delete those observations for which I do not have consecutive "return" values! - in order to apply newey west!)
ID Return Time
1 3% 01/2000
1 4% 02/2000
1 5% 03/2000
1 6% 04/2000
1 7% 05/2000
2 20% 01/2000
2 21% 02/2000
2 . 03/2000
2 22% 04/2000
2 23% 05/2000
3 . 01/2000
3 . 02/2000
3 12% 03/2000
3 13% 04/2000
3 14% 05/2000
This means, the comopany with ID 2 should be deleted but not the one with 3 or 1! (sorry if I mixed up variables and observations in my prior email!)
On Thu, Jul 26, 2012 at 9:27 PM, Braunfels, Philipp (Stud. SBE / Alumni) <[email protected]> wrote:
> Dear statlisters,
> I am asking for your advice on the following issue: I want to run a newey-west regression (to account for heteroscedasticity and autocorrelation). I have a panel of 2000 companies and their respective returns. however the returns of some companies have missing values aka "gaps". Therefore, I would like to delete all companies that have gaps in order to apply newey west. In this respect, I have also companies that have consecutive data but start at a later year than my sample (e.g. company values as of 2006 but sample starts in 2000). for the latter companies I would like to retain all values (as this should not be a problem with the newey west estimation?!?!).
>
> usually I would just write - drop if return>=. - however this would also eliminate those companies for which I have consecutive data (but start at a later date than my overall sample)
>
> I am very thankful for any advice!
>
> greets!
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/