What is a scatter diagram used for?

• A. To test a hypothesis about causation.
• B. To forecast future values.
• C. To group data into categories.
• D. To explore potential relationships or correlations between two variables.

Answer: (D)

A scatter diagram is used to see if two quantitative variables have a relationship, by plotting one variable on each axis and examining the pattern of points. If the points tend to rise together, there’s a positive relationship; if they tend to move in opposite directions, there’s a negative relationship. The strength and shape of the pattern help you judge how strong the association is and whether it looks linear or non-linear, and you can spot outliers or clusters that might affect the relationship. It doesn’t prove causation, only whether a relationship or correlation appears to exist. It also isn’t a forecasting tool by itself—predicting future values requires a model such as regression. And it isn’t used to categorize data into groups—the scatter plot shows continuous variables, not categories. So the best use is to explore potential relationships or correlations between two variables.