Re: [R] Weights using Survreg

2011-09-06 Thread Terry Therneau
I agree with David that poisson regression would be the simplest thing. It's a consequence of the poison formulation and an exponential "trick" E(#breaks) = breaks per meter * length in meters = exp(Xb) * exp(log(length)) = exp(Xb + log(length)) X = covariates that affe

Re: [R] Weights using Survreg

2011-09-06 Thread David Winsemius
I think you are replying to Dr Therneau without including this context: --- begin Survreg produces MLE estimates. For your second question, don't know what you are asking. Can you be more specific and detailed? ---begin included message -- Do you know if the parameters estimators are MLE

Re: [R] Weights using Survreg

2011-09-06 Thread Boris Beranger
Sorry when we talk about about MLE estimates does that mean WLE?I am trying to understand if the survreg function is allowing a weight for each density function when calculating the likelihood. In my second question I was trying to explain that my problem is that I have pipes of different length a

Re: [R] Weights using Survreg

2011-09-06 Thread Terry Therneau
Survreg produces MLE estimates. For your second question, don't know what you are asking. Can you be more specific and detailed? ---begin included message -- Do you know if the parameters estimators are MLE estimators? One more question: In my case study I have failures that occured on differ

Re: [R] Weights using Survreg

2011-09-02 Thread Boris Beranger
Thank you for your reply, it has been helpful. Do you know if the parameters estimators are MLE estimators? One more question: In my case study I have failures that occured on different objects that have different age and length, could I use weight to find the estimates of a weibull law and so to

Re: [R] Weights using Survreg

2011-09-01 Thread Terry Therneau
The survreg function uses case weights. That is, if a subject is given a weight of 2, the result is the same as if there were a second observation (exactly the same). Early in my career data sets that contained only categorical variables were often collapsed in just this way, in order to save on

[R] Weights using Survreg

2011-08-31 Thread Boris Beranger
Dear R users, I have been trying to understand what the Weights arguments is doing in the estimation of the parameters when using the Surreg function. I looked through the function's code but I am not sure if I got it or not. For example, if I inclue the Surv function in it: survreg(Surv(vector,