Calculate survival function for AFT model
On Dec 30, 2011, at 6:19 PM, Milan Bouchet-Valat wrote:
Le vendredi 30 d?cembre 2011 ? 12:46 -0800, thebennjammin a ?crit :
I have fit an accelerated failure time model using coxph, and have what seems to be a simple question that I can't figure out.
Please specify the exact package, functions and actual code you use. coxph(), as the name says, runs a Cox *proportional hazards* model, which is different from an accelerated failure time model.
I had the same puzzlement. I do think it is possible to construct some AFT models with survival::coxph using time in the rhs of the formula, but I do not think it is the recommended way, and I would feel much more comfortable using survreg as well.
You should use survreg (package survival) if you want to run the later family.
Given a vector of predictor values X, the survival time S[t|X] is the probability the entity will survive longer than some time t. Now, how do I calculate this for a specific value of t?
Package rms offers convenience functions to compute and plot this. See psm() and predict.psm().
In package survival the survfit function is the way to go if you want to recover S(t|X) -- David Winsemius, MD West Hartford, CT