What is the primary function of a scatter plot?

A scatter plot is a valuable graphical tool used primarily to represent the relationship between two quantitative variables. In this type of plot, each point on the graph corresponds to an observation from a dataset, with the position determined by the values of the two variables being analyzed. This dual-axis setup allows viewers to assess how changes in one variable may relate to variations in the other.

For instance, if studying the relationship between study hours and test scores, a scatter plot can visually depict how an increase in study time might correlate with higher scores. The overall pattern of the points (whether they cluster together, show a trend, or display a random distribution) can reveal important insights, such as positive or negative correlations between the variables.

The other choices refer to different methods of data presentation: displaying categorical data typically utilizes bar graphs; frequency distributions are better shown using histograms; and trends over time are more effectively illustrated with line graphs. All these forms serve specific purposes but do not capture the two-variable analysis intrinsic to scatter plots.