#-----------------------------------------
#  Diamond Pricing
#------------------------------------------


diamond = read.table("http://faculty.chicagobooth.edu/nicholas.polson/teaching/41000/diamond.txt",header=T)
colnames(diamond) = c("Weight", "Price")

# Run a regression

fit = lm(Price~Weight,data = diamond)
summary(fit)

# Plot

plot(Price~Weight,data = diamond,
     xlab="Weight (carats)",ylab = "Price (Singapore dollars)",
     main= "Bivariate Fit of Price (Singapore dollars) By Weight (carats)",
     xaxs="i", yaxs="i",pch=16)
lines(diamond[,1],fitted(fit),lwd=2,col="red")