# PSY202H1 Chapter 15: Chapter 15 - Correlation

## Document Summary

The most common correlation is the pearson correlation which measures the degree of a straight-line relationship: the pearson correlation: measures the degree and the direction of the linear relationship. For a linear relationship the data points could fit perfectly on a straight line (every time x increases by one point the value of y also changes by a consistent and predictable amount) The definitional formula instructs to perform the following sequence of operations: find the x deviation and y deviation for each individual, find the product of deviations for each individual, add the products. The computational formula uses original scores (x and y values) results in easier calculations: n = always means number of scores used, both formulas should also produce the same sp value. It is always handy to sketch the scatterplot to see a proper correlation with r. Each x value can be transformed into a z-score zx using the mean and standard deviation for the set of.