st: RE: first-difference command

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

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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