Lung Tumor Interval Censored Data from Hoel and Walburg 1972

RFM mice were sacrificed and examined for lung tumors. This resulted in current status interval censored data: if the tumor was present, this implied left censoring and if no tumor was present this implied right censoring. Mice were placed in two different groups: conventional environment or germ free environment.

Usage

miceData

Format

An object of class data.frame with 144 rows and 3 columns.

Fields

l

left side of observation interval

u

right side of observation interval

grp

Group for mouse. Either "ce" (conventional environment) or "ge" (germ-free environment)

References

Hoel D. and Walburg, H.,(1972), Statistical analysis of survival experiments, \emph{The Annals of Statistics},
18, 1259-1294

Examples

head(miceData)
#>   l   u grp
#> 1 0 381  ce
#> 2 0 477  ce
#> 3 0 485  ce
#> 4 0 515  ce
#> 5 0 539  ce
#> 6 0 563  ce
mice_ph_fit <- ic_sp_ph(Surv(l, u, type = 'interval2') ~ grp, data = miceData)

summary(mice_ph_fit)
#> Call:
#> ic_sp_ph(formula = Surv(l, u, type = "interval2") ~ grp, data = miceData)
#> 
#> Coefficients:
#>       Estimate Std.Error z.value p.value
#> grpge   0.6785    0.3537  1.9184   0.055
#> 
#> Log-likelihood: -76.56894 
#> Iterations: 28