Re: st: panel unit root test t=4 / pooled estimation

[Daniel Becker <daniel.becker@uni-rostock.de>]

... answering my own question: 4 observations in the time dimension  
are not enough ...

I guess it is so obvious that nobody felt the need to answer ... Sorry  
for the noise.

D


Am 08.08.2008 um 19:31 schrieb Daniel Becker:


> Dear statalister,
>
> maybe the question is a bit silly, but maybe someone has the time...
>
> I have a panel with 74 cross-sectional observations and 4 year  
> (1985,1990,1995,2000). I decided to ignore the time dimension and  
> did a regression that includes dummies for the last three out of the  
> four years.
>
> However, "regress depvar year" and a scatter plot suggest that my  
> dependent variable has a trend. So I thought that I should have a  
> look at stationarity. But is this necessary if I am not making use  
> of the time dimension anyway?
>
> Secondly, while exploring several tests for unit roots, that most of  
> time seem to reject the existence of a unit root, I started to think  
> whether those test really are meaningful in my case. In the end,  
> there are only 4 years in the panel. (And, in addition, I do not  
> really know what an approbiate lag-length might be.)
>
> So my questions are:
>
> Is stationarity important if the estimation is done in a pooled panel?
>
> Are panel unit-root tests valid if the time-dimension is very short?
>
> Thanks for your help,
>
> Daniel
>
>
>
>
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