A correlation of -1 means that there is a perfect negative linear relationship between variables. The scatterplot shown below depicts a negative relationship. It is a negative relationship because high scores on the X-axis are associated with low scores on the Y-axis.

A correlation of 0 means there is no linear relationship between the two variables. The second graph shows a Pearson correlation of 0.

Correlations are rarely if ever 0, 1, or -1. Some real data showing a moderately high correlation are shown on the next page.