[R] Survreg output - interpretation

[Terry Therneau]

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Hello R users,
I am analizing survival data (mostly uncensored) and want to extract the
most out of it.
Since I have more than one factor, I?ve read that the survival regression
can help to test the interactions between factors, and then decide how to do
the comparisons using the Log-rank test (survdiff).
1- if I chose the Weibull distribution, does the output inform the goodness
of fit to it? perhaps in this part of the output...

Weibull distribution
Loglik(model)= -1302.8   Loglik(intercept only)= -1311
         Chisq= 16.49 on 11 degrees of freedom, p= 0.12
Number of Newton-Raphson Iterations: 7
n= 873

2- one of my factors is "gender" (2 levels). With survreg, it appears as
significant, but if I compare them with log-rank it turns not significant.
Are they comparing different things? or is it a test power issue?

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1. To understand goodness of fit you need to look at the residuals in 
multiple ways.  (The same answer applies to ordinary linear regression.)

2. You have not given us enough information to answer the questions.  If 
the data is p=.049 vs p=.051, the the answers are in agreement even 
though the artificial label of "significant" changes.  The logrank test 
and survreg are not the same model.  If the data is p=.02 vs p=.8, then 
you have an error in the code.

Terry Therneau