If correlation coefficient is zero, no relationship exists between the variables. If one variable moves, you can make no predictions about the movement of the other variable; they are uncorrelated.
If correlation coefficient is –1, the variables are perfectly negatively correlated (or inversely correlated) and move in opposition to each other. If one variable increases, the other variable decreases proportionally. A negative correlation coefficient greater than –1 indicates a less than perfect negative correlation, with the strength of the correlation growing as the number approaches –1.
Test your understanding of how correlations might look graphically. In the box below, choose one of the three sets of purple points and drag it to the correlation coefficient it illustrates: 1, –1, or 0. If your choice is correct, an explanation of the correlation will appear. Remember to close the Instructions box before you begin.