st: pgmhaz/hshaz output, why does it look like this?

[Hilde Karlsen <Hilde.Karlsen@hio.no>]

Dear statalisters,

I am having trouble understanding why the result of my pgmhaz-command 
ends up like shown in the output below. (Why are there "missing" values 
on several of the estimates?)

Does this imply I should not use pgmhaz for my discrete time hazard 
analysis? I've tried hshaz, but it yielded the same result. Moreover, 
constructing the baseline hazard in a different manner (for example 
log(time), or creating finer time units with dummy variables) also does 
not solve this problem. I am trying to find out wether there is 
significant heterogeneity in the data, and the first analysis (nocons) 
suggested statistically significant frailty. Should I rather be using a 
different command/program?


Here is my syntax and output; I hope it is readable.


---------

. pgmhaz  year1_4 year5_7 year8_10 male, i(LPNR) s(year) d(movedout)

PGM hazard model with Gamma heterogeneity	

Number of obs	=   16181
Model chi2(3)	=       .
Prob > chi2	=       .
Log Likelihood =  -1003.6567957

		
movedout    Coef.      Std. Err.      z	  P>z
		
hazard
year1_4   -.5213477   .1809304    -2.88	  0.004
year5_7   -.0568201          .        .	    .
year8_10   .1837397    .218296     0.84	  0.400
_cons   -4.199123     .1344249   -31.24	  0.000
		
ln_varg
_cons   -14.54299          .        .	.
		
Gamma variance, exp(ln_varg) = 4.831e-07; Std.	Err. = 0; z = .
--------

Regards,
Hilde

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