Pearson correlation coefficient

Pearson's correlation is a mathematical formula for calculating how similar two sets of data are (their correlation). The results of the formula are the correlation coefficients between the two sets. Most computer programs have a command to calculate this such as CORREL(dataset x: dataset y). The coefficient can be calculated by

 Step 1: Find the mean of x, and the mean of y
 Step 2: Subtract the mean of x from every x value (call them "a"), and subtract the mean of y from every y value (call them "b")
 Step 3: Calculate: ab, a2 and b2 for every value
 Step 4: Sum up ab, sum up a2 and sum up b2
 Step 5: Divide the sum of ab by the square root of [(sum of a2) × (sum of b2)]


Karl Pearson came up with the formula in the 1880s when he contributed to research in statistics.

Category:Statistics