[R] Software Reliability Using Cox Proportional Hazard

[voodooochild@gmx.de]

Hello,

i want to use coxph() for software reliability analysis, i use the 
following implementation

#######################################################################################
failure<-read.table("failure.dat", header=T)
attach(failure)

f<-FailureNumber
t<-TimeBetweenFailure

# filling vector f with ones

for(i in 1:length(f)) {
  f[i]<-1
}

library(survival)

# cox proportional hazard with covariable LOC

cox.res<-coxph(Surv(t,f)~LOC,data=failure)
plot(survfit(cox.res))
##########################################################################################


failure.dat is
FailureNumber TimeBetweenFailure    LOC
1    7        120
2    11        135
3    8        141
4    10        150
5    15        162
6    22        169
7    20        170
8    25        181
9    28        188
10    35        193

here TimeBetweenFailure gives the time between following failures and 
LOC is the actuall Lines of Code.
What i do, is filling the vector f with ones. f is then in Surv the 
censoring variable. in survival analysis the censoring variable is 1 if 
the patient dies, now i interpret the event death as
the appearence of a failure. And i use LOC as covariable.

My question now is, is this approach right or is there any big mistake 
or wrong interpretation?


Thanks a Lot!
best regards
Andreas