# PropVal2 Example -- source code file propval2.r

# Read and print data frame.
propval = read.table("propval.txt", header=T, skip=13)
cat("propval data frame:\n")
print(propval)

# Define full model.
fullmodel = lm(y ~ x2+x3+x4+x5+x6+x7+x8+x9, data=propval)

# Perform forward selection:
cat("\nForward Selection:\n")
model = lm(y ~ 1, scope=fullmodel, data=propval)
summary(step(model, direction="forward"))

# Perform backward selection:
cat("\nBackward Selection:\n")
summary(step(fullmodel, direction="backward"))

# Perform stepwise selection:
cat("\nStepwise Selection:\n")
summary(step(fullmodel))