# Spache Shuttle Challenger O-Rings
#
# The 1986 crash of the space shuttle Challenger was linked to failure 
# of O-ring seals in the rocket engines. Data was collected on the 23 
# previous shuttle missions. The launch temperature on the day of the 
# crash was 31F.
#
# A data frame with 23 observations on the following 2 variables.
# temp: temperature at launch in degrees F
# damage: number of damage incidents out of 6 possible
#
# Source: Presidential Commission on the Space Shuttle Challenger 
# Accident, Vol. 1, 1986: 129-131.
#
# References: S. Dalal, E. Fowlkes and B. Hoadley (1989) "Risk Analysis 
# of the Space Shuttle: Pre-Challenger Prediction of Failure." 
# Journal of the American Statistical Association. 84: 945-957.
#
# Disclaimer: Documentation reproduced from package faraway, 
# version 1.0.7, License: GPL

install.packages("faraway")
library("faraway")
attach(orings)

n = length(temp)
x = temp
y = damage
y[y>1]=1
x1 = x + rnorm(n,0,0.3)
plot(x1,y,xlab="temperature at launch in degrees F",ylab="Damage",cex=0.75)