# R script for InfluenceSimulation Example

xorig = rnorm(50)
yorig = rnorm(50)

pdf("inf-sim.pdf")

# Model 1
x = c(xorig, 20)
y = c(yorig, 20)
modelorig = lm(yorig ~ xorig)
model1 = lm(y ~ x)
cat("Influence points for Model 1:\n")
print(influence.measures(model1))
plot(x, y, main="InfluenceSimulation Example -- Model 1")
abline(modelorig, lty="dotted", col="blue")
abline(model1, lty="dashed", col="red")
subset = c(17, 51)
points(x[subset], y[subset], col="red", pch="*", cex=2)

# Model 2
x = c(xorig, 0)
y = c(yorig, 20)
model2 = lm(y ~ x)
cat("Influence points for Model 2:\n")
print(influence.measures(model2))
plot(x, y, main="InfluenceSimulation Example -- Model 2")
abline(modelorig, lty="dotted", col="blue")
abline(model2, lty="dashed", col="red")
subset = c(10, 17, 27, 28, 47, 51)
points(x[subset], y[subset], col="red", pch="*", cex=2)

dev.off( )