st: xttobit

["naim cordemans" <nacordemans@hotmail.com>]

I've perform regressions using xttobit and left censored explanatory 
variable in order to find the determinants of foreign aid allocations. I did 
regressions country by country for the USA, Japan and the main UE donors 
over three period of time : 1980-1989 ; 1990-1999 and 2000-2003.
I got most of the results but for some regressions, results are missing 
(replaced by dots) and I can get the value of either the standard error and 
the significativity level (Z). I checked all the data's twice and perform 
the regressions where results were missing twice but I still don't 
understand why I can't get some results. Could somoeone give me information 
about that?

thank you very much

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