st: discrete time survival analysis and logit model

[Fen Lin <lin@galton.uchicago.edu>]

Dear all,

I am using a discrete time survivial model to analyze diffusion a policy 
among 30 countries. My data is in a person-period structure, so i have 
30 sequences but 1228 data points. In stata, i use logit command:

logit y x1 x2 x3 ln(duration), cluster(country)

so the standard errors will be adjusted by cluster. i am wondering:

1) is the deviance adjusted by cluaster as well? in the output, number of 
observation is 1228, rather than 30. Is it correct?

2) since my time interval is each year, i have lots of zero in certain 
year, and a tie in others (that is why i use discrete time model). but i 
cannot use "dhaz" command due to those zeros. there is always a message 
"no variation in event occurence in period 1".  in this case, how can i 
calculate hazard?

3) my predicted probablity is between 0.002 to 0.35. how come the phat 
never larger than 0.5? ( i think it might because i use "country" as unit 
of analysis, then i have omiting variable bias.??)

Thanks for reading and helping!

fen
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