Dear R-listers,
 
Does anybody know what is the correct source of "rats" dataset in survival package?
 
The help gives the following information:
 
Rat data from survival5
Description:
     48 rats were injected with a carcinogen, and then randomized to
     either drug or placebo.  The number of tumors ranges from 0 to 13;
     all rats were  censored at 6 months after randomization.
Usage:
     data(rats)
Format:
       rat:          id
       rx:           treatment,(1=drug, 0=control)
       observation:  within rat
       start:        entry time
       stop:         exit time
       status:       event status
Source:
     Gail, Sautner and Brown, Biometrics 36, 255-66, 1980
 
but "rats" data.frame contains the variables:
 
names(rats)
[1] "litter" "rx"     "time"   "status"
 
It seems to be 150 rats grouped in 50 litters, and 1 mouse is treated at each one. So this dataset does not agree with the description above mentioned. 
 
I am very interesting in knowing the reference of this data.
 
PS/ BTW, the correct source of  rats injected with a carcinogen is Gail, Santner and Brown,...
 
Thanks you very much in advance,
 
Juan
 
 
 
 
 

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