Dear R users:
 
I am using survreg for modeling left censored longitudinal data. When I am using the following code for fitting the tobit model I am getting some output with an warning message(highlighted with red color):
 
> survreg(Surv(y, y>=0, type='left')~x + frailty(id), cytokine.data, weight=w, dist='gaussian', scale=1)

Call:
survreg(formula = Surv(y, y >= 0, type = "left") ~ x + frailty(id), 
    data = cytokine.data, weights = w, dist = "gaussian", scale = 1)
            coef    se(coef) se2     Chisq   DF   p      
(Intercept) -1.5099 0.3626   0.24322    17.3    1 3.1e-05
x            0.0404 0.0079   0.00493    26.2    1 3.0e-07
frailty(id)                          13853.2 1039 0.0e+00
Scale fixed at 1 
Iterations: 10 outer, 72 Newton-Raphson
     Variance of random effect= 12.1   I-likelihood = -20098.2 
Degrees of freedom for terms=    0.5    0.4 1039.4 
Likelihood ratio test=232877  on 1039 df, p=0
  n=4840 (57 observations deleted due to missingness)
Warning message:
Inner loop failed to coverge for iterations 2 in: survpenal.fit(X, Y, weights, offset, init = init, controlvals = control,  
> 

Could you please help me in finding the error in my code (if any) so that I will not get this error message? I would really appreciate if you could help me in this regard. 
 
Thank you so much. 
 
Sincerely, 
 
Sattar


 
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