Abrasion loss of rubber specimens

Use this diagram to explain how the plotting symbol can represent a third numerical variable in a scatterplot. Use the pop-up menu to select different representations.

In this example, abrasion loss is the response variable. What combinations of tensile strength and hardness correspond to high abrasion loss?

Mention that it is often hard to interpret this kind of diagram.

In an industrial experiment, 30 rubber specimens were rubbed by an abrasive material. The measurements from each specimen were ...

tensile strength
force per unit cross-sectional area required to break the specimen
hardness
rebound height of a steel indenter dropped onto the specimen
abrasion loss
amount of material abraded from the specimen per unit of energy expended in rubbing it.