Re: Question about survReg

[Terry Therneau <therneau@mayo.edu>]

  The survreg function uses location-scale parameterization, which is one
of about 4 ways to write down the Wiebull distribution.  The best
reference on the parameters is Kalbfleisch and Prentice, The Statistical
Analaysis of Failure Time Data, section 2.2.2 (I have the older version, the
chapter number may now be different).

  If you write the Wiebull as
        f(t) = lambda p (lambda t)^(p-1) exp[-(lambda t)^p]
then

        1/p = sigma and -log(lambda) = intercept.
        

  This is, however, only one of many ways to write a Weibull.  Different
disciplines seem to have their own "canonical" form.  So the direct answer
to your query
        " 1/sigma = shape"
        " exp(-intercept/sigma) = scale"

is that I don't know unless you write out your favored Wiebull formula for us.


        Terry Therneau