[R] meaning of frailty estimates

[Emanuela Rossi]

Here the output. "Specie" is the frailty variable, with four types of
answer. I'm asking what's the meaning of gauss:1, ....gauss:4

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>
SURV1<-read.table("C:/LAVORO/MOBILE/survival/surv_n1.csv",header=TRUE,sep=",
")
> fit_13_2_sp<-coxph(Surv(DATA_INI1,DATA_FIN1,EVENT1)~
V1+V2+Z+G+dim+frailty.gaussian(specie)+cluster(ID),data=SURV1)
> summary(fit_13_2_sp)
Call:
coxph(formula = Surv(DATA_INI1, DATA_FIN1, EVENT1) ~ V1 + V2 +
    Z + G + dim + frailty.gaussian(specie) + cluster(ID), data = SURV1)

  n= 233450
                         coef       se(coef)   se2             Chisq  DF
p
V1                  0.04995   0.14021  0.145916    0.13  1.00  7.2e-01
V2                 -0.79656   0.20483  0.197135  15.12 1.00  1.0e-04
Z                    -0.00359  0.00067  0.000841   28.76 1.00  8.2e-08
G                     0.08186  0.00583  0.005796 196.91 1.00  0.0e+00
dim                  0.39410  0.06981  0.057294   31.87 1.00  1.6e-08
frailty.gaussian(specie)                                    181.44 2.95
0.0e+00

        exp(coef) exp(-coef) lower .95 upper .95
V1          0.951      1.051     0.723     1.252
V2          0.451      2.218     0.302     0.674
Z           0.996      1.004     0.995     0.998
G           1.085      0.921     1.073     1.098
dim         1.483      0.674     1.293     1.700
gauss:1     2.504      0.399     2.108     2.975
gauss:2     1.799      0.556     1.457     2.221
gauss:3     0.278      3.599     0.217     0.356
gauss:4     0.799      1.252     0.641     0.996

Iterations: 5 outer, 11 Newton-Raphson
     Variance of random effect= 0.975
Degrees of freedom for terms= 1 1 1 1 1 3
Rsquare= 0.003   (max possible= 0.025 )
Likelihood ratio test= 810  on 7.95 df,   p=0
Wald test            = 600  on 7.95 df,   p=0,   Robust = 355  p=0

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Thanks

Emanuela


----- Original Message ----- 
From: "Thomas Lumley" <tlumley at u.washington.edu>
To: "Emanuela Rossi" <emanuela.rossi at unimib.it>
Cc: <r-help at stat.math.ethz.ch>
Sent: Thursday, October 28, 2004 4:08 PM
Subject: Re: [R] meaning of frailty estimates


> On Thu, 28 Oct 2004, Emanuela Rossi wrote:
>
> > Hello,
> >
> > I'm trying to estimate a Cox's survival model with a random effect, so I
> > have added the instruction frailty.gaussian (name variable) in the
> > model.
> >
> > My frailty variable is a qualitative variable with four types of answer.
> >
> > In the resulting output there are the parameter estimates of all the
> > variables, but there are also four estimates for each type of answer of
> > the frailty variable. Which kind of estimates are they? Maybe hazard
> > ratio? But which is the reference?
> >
>
> Perhaps you could post this output so we know what you are talking about.
>
>   -thomas
>