Correlation Coefficient

By Courtney Taylor, About.com Guide

The correlation coefficient, typically denoted r measures how strongly two numerical variables are linked to each other. The following is the formula for r, with a brief description of the variables:

• The number of data points is given by n.
• The capital sigma denotes addition of several terms.
• The data points are represented by x_i and y_i.
• The mean of the x_i is denoted by x with a horizonatal bar over it.
• The standard deviation of the x_i is denoted by s_x.
• The mean of the y_i is denoted by y with a horizonatal bar over it.
• The standard deviation of the y_i is denoted by s_y.