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Re: st: RE: dropping observation


From   "Eric A. Booth" <ebooth@ppri.tamu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: dropping observation
Date   Wed, 10 Jun 2009 17:40:17 -0500

Probably lots of ways to do this, but I would:

bysort analystID: egen max = max(employerID)
bysort analystID: egen min = min(employerID)
drop if max==min

Eric

__
Eric A. Booth
Public Policy Research Institute
Texas A&M University
ebooth@ppri.tamu.edu
Office: +979.845.6754
Fax: +979.845.0249


On Jun 10, 2009, at 5:36 PM, Stefano Bonini wrote:

thanks Kieran

unfortunately in the example I know that I have to drop analyst 1 (visual inspection makes it easy) but I have thousands of analysts with thousands of forecasts and visual inspection is not an option for identifying who needs to be dropped.


----- Original Message -----
From: "Kieran McCaul" <Kieran.McCaul@uwa.edu.au>
To: statalist@hsphsun2.harvard.edu
Sent: Wednesday, June 10, 2009 6:31:00 PM GMT -05:00 US/Canada Eastern
Subject: st: RE: dropping observation

..

drop if analystID==1

______________________________________________
Kieran McCaul MPH PhD
WA Centre for Health & Ageing (M573)
University of Western Australia
Level 6, Ainslie House
48 Murray St
Perth 6000
Phone: (08) 9224-2701
Fax: (08) 9224 8009
email: Kieran.McCaul@uwa.edu.au
http://myprofile.cos.com/mccaul
http://www.researcherid.com/rid/B-8751-2008
______________________________________________
Man is a credulous animal, and must believe something; in the absence of good grounds for belief,
he will be satisfied with bad ones. Bertrand Russell


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu ] On Behalf Of Stefano Bonini
Sent: Thursday, 11 June 2009 6:18 AM
To: statalist@hsphsun2.harvard.edu
Subject: st: dropping observation

Hi
I have a huge panel dataset containing analyst forecasts. Each analyst is associated with an employer. Sometimes analyst change employer. I want to restrict my dataset, dropping the observations of analysts that never change employer. The dataset may look like this

forecast#     analystID   employer ID
1                 1            1
2                 1            1
3                 1            1

1                 2            1
2                 2            1
3                 2            2
4                 2            2

1                 3            3
2                 3            4

In this case I'd nee to drop all observations by analyst 1 because he never changes employer, while keeping those of analysts 2 and 3.

I really cannot figure out the way to do it as visual inspection is just impossible with over 1.2m obs.

Thanks!

Stefano
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--
Stefano Bonini
Visiting Associate Professor
Department of Finance
New York University
Stern School of Business
44W 4th St. New York, NY

Ph. +1 212 998 0305
Email sbonini@stern.nyu.edu
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