# Sample R Code for simple linear regression


x=c(1,2,3,4)        # enter x values
y=c(1.1,2,3.5,4.2)  # enter y values

plot(x,y) # create scatterplot of x and y

xbar=mean(x) # calculate sample mean of x
print(xbar)  

ybar=mean(y) # calculate sample mean of y
print(ybar)  

sx=sd(x)     # calculate sample sd of x
print(sx)

sy=sd(y)     # calculate sample sd of y
print(sy)

r=cor(x,y)   # calculate sample correlation coefficient between x and y
print(r)

betahat=r*(sy/sx)            # calculate sample estimate of slope
print(betahat)

alphahat=ybar-(betahat*xbar) # calculate sample estimate of intercept
print(alphahat)

summary(lm(y~x))  # check calculations with R's built-in function
# abline(lm(y~x))  # Superimpose the fitted regression line on the scatterplot