What does a scatterplot graphically display?

• A. A graph that plots values of one variable against those of another, possibly including a third variable in 3-D.
• B. A line graph of a time series.
• C. A histogram of a single variable.
• D. A box plot across categories.

Answer: (A)

A scatterplot visually displays the relationship between two quantitative variables by plotting each observation as a point with one variable on the horizontal axis and the other on the vertical axis. This setup lets you see patterns such as direction (positive or negative), strength, and whether the relationship is linear or nonlinear, as well as identify clusters and outliers. A third variable can be explored by using a 3-D plot or by varying color or point size to encode the additional dimension. The other options describe different types of graphs: a line graph of a time series shows change over time; a histogram shows the distribution of a single variable; a box plot compares distributions across categories.