ABSTRACT
The first thing to recognize with correlation is that it works best when the relationship between two variables is linear. A linear relationship between two variables is one in which the relationship can best be represented by a straight line. The strength of the relationship between two variables can be expressed statistically as a correlation coefficient and can vary from +1.00 to -1.00. A major problem in measuring the relationship between two variables is that very often the variables are measured on different scales and in different units. The Pearson product-moment correlation coefficient is a measure of the strength and direction of the linear relationship between two variables. A spurious correlation is a statistical term that describes a situation in which two variables have no direct connection (correlation), but it is incorrectly assumed they are connected as a result of either coincidence or the presence of a third hidden (confounding) factor.
