This video looks at what Pearson's correlation coefficient is and how we use it to relate the closeness of the points of a scatter plot to the line of best fit (otherwise called the Least Squares Regression Line). It is part of the VCE General Maths course (Year 11) and relates to the module of work on Data and Statistics. A brief look at how it is calculated is followed by a discussion of the table and what it means. Then, strangely we look at the ideas behind Correlation and Causality! Looking at Common Responses, Confounding Variables and Coincidences, we decide which can explain a relationship between two numerical variables. There are a number of worked examples and explanations which "just make sense".