Strength of associations

Textbooks provide plots with dots showing:

• no association
• moderate association
• strong association

for both positive and negative associations.

They will look similar to the diagrams below.

Association is measured with the correlation coefficient, where no association relates to a correlation of 0, a very strong positive association has a correlation near +1 and a very strong negative association has a correlation near –1.

Strength of associations.

Examples of scatter plots and an activity can be be found in Is There an Association? and Judging Associations.