Weekly salary and age of mid-level executives

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 of the variable employment length.

For any specific age, the salary tends to be higher for those who have had a shorter length of employment with the company. Presumably recent employees have been attracted with higher salaries!

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

These data are artificial. The personnel department of a large company is examining the salaries of its mid-level executives. The scatterplot below shows the weekly salaries of the 32 executives, their ages and the number of months of employment.