# for Topic 8a
    #  first get our two sets of values
x <- c( 10, 19, 15, 10, 7, 5)
    #
y <- c( 27, 32, 33, 19, 25, 20)
    #  get a generic plot
plot(x,y)
     # then make a much better plot
plot(x,y, main="Data for Topic 8a",
     xlim=c(-1,21), ylim=c(-1,39),
     las=1, xlab="x axis", ylab="y axis",
     xaxp=c(0,20,10), yaxp=c(0,40,8),
     pch=19, col="red")
abline(v=0,h=0)
abline(v=seq(2,20,2), h=seq(5,40,5),
       lty="dotted", col="darkgreen")
     # draw the line through (6,18) and (20,35)
abline(25/2, 5/4, col="blue", lty="dashed")

m <- 5/4
c <- 25/2
diffoe <- y - (m*x+c)
diffoe
sum( diffoe^2)



cor(x,y)

lm(y~x)