You generate a scatter plot using Excel.

Question

You then have Excel plot the trend line and report the equation and the r² value. The regression equation is reported as y=13.45x+19.64 and the r²0.7744.

What is the correlation coefficient for this data set?

Answer 1

r = ± √(r^2)

We determine the sign by looking at the sign of the x coefficient in the regression equation. In this case, it is a + (13.45x)

Thus, r = + √.7744 = .88