Construct a scatterplot for the (x, y) values below, and answer the following questions. You do NOT need to submit your scatterplot with your answer; however, show all other work.
X Y
1 -5
2 -10
3 =15
4 -20
5 -25
Plot the five points
(1,-5), (2,-10), (3,-15), (4,-20), (5,-25)
Hmm! This is different from most scatter plots because it is
possible to draw a straght line through all 5 points. Usually this
is not possible and we have to find the line that comes the closest
to fitting them all. But this one is different, because they all
lie on the same line, as you can see
What would be the slope of this regression line?
Just pick any two of the points and use the slope formula.
Suppose we pick the points (2,-10) and (4,-20)
Would the correlation between x and y be positive or negative?
It would be negative since the slope is negative.
How would you interpret these data in terms of linear regression?
Since the regression line fits all the points perfectly, and the points
move down to the right, the correlation coefficient is -1.
Edwin
