delivery=read.csv("http://chase.mathstat.dal.ca/~bsmith/stat3340/Data/delivery.csv",header=T)
delivery[1:4,] #print first 4 rows of delivery

pairs(delivery) #pair plots

delivery.lm=lm(y~x1+x2,data=delivery) #multiple linear regression of y on x1,x2, put results in delivery.lm
summary(delivery.lm) #look at the output of the regression

delivery0.lm=lm(y~1,data=delivery) #fit a model which only includes an intercept, but neither x1 or x2

anova(delivery.lm,delivery0.lm)   #carry out an analysis of variance to assess the overall
#significance of the model.  That is, text H0: beta_1=beta_2=0.


#fit a model which includes x1 and x2, but no intercept
delivery.noint=lm(y~x1+x2-1,data=delivery) #multiple linear regression of y on x1,x2, put results in delivery.lm

#carry out an F test to compare delivery.noint and delivery.lm
anova(delivery.noint,delivery.lm)