Correlation is one of the most fundamental and useful tools when comparing variables within the social sciences. This statistic gives a numeric quantity to the strength of the relationship and as importantly the direction of the relationship between these variables. With all the usefulness correlation provides in describing relationships, there is one fundamental flaw with correlational research. It does not show causality, but there is a related problem. The dreaded and unidentified third variable. Identify an example of where either a positive or negative correlation exists between two variables where they are both being influenced by an unrelated circumstance (the third variable).