What is the primary use of a scatter plot?

A scatter plot is primarily used to visualize the relationship between two quantitative variables. This is accomplished by plotting points on a Cartesian plane, where each axis represents one of the variables. The position of each point on the graph indicates the values for both variables for a particular observation. By examining the pattern of points, one can determine whether a relationship exists, whether it is positive, negative, or if there's no correlation at all.

This tool is particularly effective for identifying trends, assessing the strength of a relationship, and even hinting at the type of relationship (linear, non-linear) present between the variables. The visual representation makes it easier to interpret complex data relationships that might be less clear through numerical measures alone. For instance, if the points cluster along a straight line, this would suggest a strong linear relationship. Scatter plots are fundamental in exploratory data analysis and are crucial in understanding and describing correlations in data sets.