Question

These data were generated using the equation y = 2x + 1. A scatter diagram of the data results in five points that fall perfectly on a straight line.

x 0 1 2 3 4
y 1 3 5 7 9

(a) Find the correlation coefficient.

Answer 1

1.0
When data fit exactly onto a straight line, the correlation coefficient is either +1 or -1.
If the slope of the line is positive, r=+1. If the slope of the line is negative, r=-1.
In this case, the slope=+2, so r=+1.0