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Re: st: RE: Spotting changes in identifier


From   "Pavlos C. Symeou" <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: RE: Spotting changes in identifier
Date   Wed, 07 Jul 2010 14:05:50 +0200

thanks for the reply. As you suggest I omit the "" but what the new command returns is the last year-observation for all companies in my dataset.

Is there a possible explanation for that?

Best,

Pavlos



On 07/07/2010 13:12, Nick Cox wrote:
You tried

bysort name: l name ticker year if ticker[_n]!="ticker[_n+1]"

but you need to omit the " ". What you typed is legal, but the literal text

"ticker[_n+1]"

presumably never is an actual value of -ticker-, so this will list all the data, as every value of ticker is indeed not equal to that text.

As said, omit the "".

Nick
[email protected]

Pavlos C. Symeou

I have panel data on a number of companies over a series of years.
Two of my variables uniquely identify an observation (Name and
Ticker). For different reasons:
a) the Name may have changed over the years whilst the Ticker may
have remained the same;
year      name   ticker
1999    stata   ss
2000    strata ss

b) the Ticker may have changed over the years whilst Name may have
remained the same;
year      name   ticker
1999    stata   ss
2000    stata   sss

c) both may have changed

year      name   ticker
1999    stata   ss
2000    strata sss


I am interested in identifying cases a) and b) above (considering
that case c might require visual observation rather than an
automated process)

Do you have any suggestions?

I have tried

bysort name: l name ticker year if ticker[_n]!="ticker[_n+1]"

but it doesn't seem to work. Both Name and Ticker are string variables.


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