Correct Interpretation of survreg() coeffs
On May 4, 2012, at 9:43 AM, wwreith wrote:
Am I correct in assuming that the output below essentially translates to "Males have a mean time that is significantly lower than Females"? Is this the correct way to interpret the fact that the coefficient is negative?
I wouldn't be using exactly that phrasing since I do not think AFT models are estimating means. I might say the "point estimate for the time to event for Sex==Male is lower than for the Female". You should plot the predicted survival curves. I also do not think the inferential statistics allow you to say that the difference is "significantly different". Your z-stat is only -1.28 and your p-value is only 0.202.
Assume the variale sex is treated as a factor with Female =0 and
Male=1.
survmodel<-survreg(survobj~sex,data=data1, dist="weibull")
survsum<-summary(survmodel)
survsum
Value Std. Error z p
SexMale -0.47830 0.3745 -1.2770 2.02e-01
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David Winsemius, MD Heritage Laboratories West Hartford, CT