Correlation And Regression

Question 1

What is the formula for Karl Pearson’s coefficient (r)?

Answer 1

r = (∑XY) / (√∑X² • √∑Y²)
Where X = x - x̄ ; x̄ = mean of x
Y = y - ȳ ; ȳ = mean of y
Note that (∑XY) is defined as the covariance of x and y.

Question 2

What are the normal equations for methods of least squares (Regression line)

Answer 2

∑Y = an + b∑X
∑XY = a∑X + b∑X²