[R] survreg: fitting different location parameters

[h.brunschwig@utoronto.ca]

Hi R-Help! 

My question: I have lifetime/failure data of machines with different 
stress levels and i think an weibull/extreme value distribution would 
fit this data. So I did: 

model1      <- survreg(Surv(lfailure)~stress,data=steel,dist="extreme") 

(where lfailure=log(failure)) 

Now I would like to do a likelihood ratio test to test the hypothesis 

H0: location parameters of the extreme value distribution are equal 
for each stress level. 

So in order to perform the likelihood ratio test I need the likelood 
of the model under 

HA: location parameters are not equal (i.e. each stress level has its 
slope and intercept). 

How can I do this? 

Thanks for any help! 

Hadassa