springs {SMPracticals}

Spring Failure Data

Description

Failure times of 60 springs divided into 6 groups of 10, with each group subject to a different level of stress. Some of the times are right-censored.

Usage

data(springs)

Format

A data frame with 60 observations on the following 3 variables.

cycles

failure times (in units of $10^3$ cycles of loading)

cens

censoring indicator, with 0 indicating right-censoring

stress

a factor giving the stress (N/mm$^3$)

Source

Cox, D. R. and Oakes, D. (1984) Analysis of Survival Data. London: Chapman and Hall/CRC Press.

Examples

data(springs)
attach(springs)
plot(cycles~stress)
plot(cycles~stress,log="y")