An association between two variables in a scatterplot is shown by most of the points following a pattern. This pattern can be linear or non-linear. The more closely the points seem to follow this pattern, the stronger the association.
An association in a scatterplot can be negative, meaning that as one variable increases the other decreases, or positive, meaning that as one variable increases the other increases as well. A negative association will appear to decrease on a graph, and a positive association will appear to increase on a graph.
