[R-sig-Epi] lognormal distribution in survreg (Mariana Wagner)

[Thomas Lumley]

On Mon, 6 Aug 2007, Lazarus Mramba wrote:

> Hi Mariana,
>
> The log(scale)=0.40546 output means that if you want to get the scale,
> then, you compute the exponential of the coefficients 0.40546 and the
> answer will be 1.5

And this 1.5 is the standard deviation of a normal distribution, ie, of 
the log of survival time.

 	-thomas

> The sclae for the standard error can be found by  computing the
> exponential of 0.0594, giving 1.0611996
>
> Is that clear?
>
> Kind regards,
>
>
> Lazarus Mramba
>
> P.O Box 230, 80108,
> Kilifi, Kenya
> Mobile No. +254721292370
>
> (office extension : 419)
>
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>   1. lognormal distribution in survreg (Mariana Wagner)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 04 Aug 2007 09:51:33 +0200
> From: Mariana Wagner <marianaw at web.de>
> Subject: [R-sig-Epi] lognormal distribution in survreg
> To: r-sig-epi at stat.math.ethz.ch
> Message-ID: <1592232557 at web.de>
> Content-Type: text/plain; charset=iso-8859-15
>
> I fit a lognormal model to survival data using survreg.  I am confused
> about the output, because I do not know how to interprete the
> "scale." The output is:
>
> Call:
> survreg(formula = surv1 ~ p$score, dist = "lognormal")
>               Value Std. Error     z         p
> (Intercept)   5.5891     0.1986 28.14 2.76e-174
> p$score      -0.0162     0.0102 -1.58  1.14e-01
> Log(scale)    0.4046     0.0594  6.81  9.65e-12
>
> Scale= 1.5
>
> Log Normal distribution
> Loglik(model)= -996.1   Loglik(intercept only)= -997.4
>        Chisq= 2.5 on 1 degrees of freedom, p= 0.11
> Number of Newton-Raphson Iterations: 4
> n= 505
>
> Is scale the scale parameter of the lognormal distribution ? If yes is
> there no estimate of the standard derivation?
>
> Thanks,
>
> Mariana
>
>
>
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Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle