RE: Re : st: RE: first-difference command

[Mauro Mastrogiacomo <M.Mastrogiacomo@cpb.nl>]

Sure, this means that you have 75 firms! If you have two observations per firm there is only one difference per firm.
Mauro

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of donsaane dontsi
Sent: vrijdag 16 september 2011 22:05
To: statalist@hsphsun2.harvard.edu
Subject: Re : st: RE: first-difference command

 When I use this command: bys firmcode: gen dx = x-x[_n-1], I have 75 missing values generated, although when I use: gen dx=x-x[_n-1], I have only one missing values generated. I' m wondering if I could just use the last command. 

Thanks 
 
dsd


----- Mail original -----
De : Mauro Mastrogiacomo <M.Mastrogiacomo@cpb.nl>
À : "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Cc : 
Envoyé le : Vendredi 16 Septembre 2011 15h40
Objet : st: RE: first-difference command

Sorry I missed your original message but I suppose you want to code:
bys firmcode: gen dx = x-x[_n-1]

another option could be:
xtset firmcode year
gen dx=D.x

mauro


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of donsaane dontsi
Sent: vrijdag 16 september 2011 21:27
To: statalist@hsphsun2.harvard.edu
Subject: st: first-difference command

Thanks Austin, 
 
Maybe I was misunderstood. My panel dataset is sort by
year, so I have : 
firmcode year 
1        2006
1        2009
2        2006
2        2009
 
I want to first-difference all my variables in order to
be x[2006-2009]
Can I just do: gen dx=x-x[_n-1]
 
Thanks for the help

 
dsd

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