Determine areas where bubbles differ in size from adjacent bubbles. More consistency in bubble size in certain areas means there is less variation in the relationship between the variables. Less consistency in the bubble size in certain areas means there is more variation in the relationship.
For example, this graph shows the relationship between the savings, income, and amount of debt for consumers who apply for a bank loan. Larger bubbles (more debt) are clustered where savings and income are low. Smaller bubbles (less debt) occur where income is approximately 35,000 to 70,000, regardless of savings.
The bubbles get smaller as the amount of savings gets larger. There appears to be a stronger relationship between savings and debt when savings is high (where most of the bubbles tend to be small) than when savings is low (where bubbles are more mixed in size). This mixed pattern indicates some variation in the relationship.