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# Sales Example -- R source code file sales.r #
################################################

# car library should have been previously loaded with
# install.packages("car")

# Load car library for vif function.
library(car)

# Load and print data frame.
sales = read.table("sales.txt", header=T)
cat("sales data frame:\n")
print(sales)

# Model 1:
model1 = lm(Profit ~ Area + Popul + Outlets + Commiss,
   data=sales)
cat("R output for model 1:\n")
print(summary(model1))
print(influence.measures(model1))
print(vif(model1))

# Model 2:
model2 = lm(Profit ~ Area + Outlets + Commiss,
   data=sales)
cat("R output for model 2:\n")
print(summary(model2))
print(influence.measures(model2))
print(vif(model2))