Re: st: RE: Spotting changes in identifier

["Pavlos C. Symeou" <p.symeou@lmu.de>]

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
> n.j.cox@durham.ac.uk
>
> 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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