motors {MASS}R Documentation

Accelerated Life Testing of Motorettes

Description

The motorette data frame has 40 rows and 3 columns. It describes an accelerated life test at each of four temperatures of 10 motorettes, and has rather discrete times.

Arguments

temp the temperature (degrees C) of the test
time the time in hours to failure or censoring at 8064 hours (= 336 days).
cens an indicator variable for death

Format

This data frame contains the following columns:

Source

Kalbfleisch, J. D. and Prentice, R. L. (1980) The Statistical Analysis of Failure Time Data. New York: Wiley.

taken from

Nelson, W. D. and Hahn, G. J. (1972) Linear regression of a regression relationship from censored data. Part 1 – simple methods and their application. Technometrics 14, 247-276.

Examples

library(survival5)
data(motors)
plot(survfit(Surv(time, cens) ~ factor(temp), motors), conf.int=FALSE)
# fit Weibull model
motor.wei <- survreg(Surv(time, cens) ~ temp, motors)
summary(motor.wei)
# and predict at 130C
unlist(predict(motor.wei, data.frame(temp=130), se.fit=TRUE))

motor.cox <- coxph(Surv(time, cens) ~ temp, motors)
summary(motor.cox)
# predict at temperature 200
plot( survfit(motor.cox, newdata=data.frame(temp=200),
     conf.type="log-log") )
summary( survfit(motor.cox, newdata=data.frame(temp=130)) )

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