When comparing bar graphs and line graphs, which statement is accurate?

• A. Bar graphs show proportions; line graphs show means.
• B. Bar graphs compare across conditions or individuals; line graphs show changes over time.
• C. Bar graphs show time trends; line graphs compare individuals.
• D. Bar graphs show within-subject data; line graphs show between-subject data.

Answer: (B)

Bar graphs are used to compare values across different conditions or individuals at a single point in time. Each bar represents a summary value for a category, so you can quickly see which condition or person has a higher or lower value. Line graphs, on the other hand, show how data change over time or across an ordered sequence; by plotting successive points and connecting them, you can observe trends, increases, or decreases across sessions. So, the statement that bar graphs compare across conditions or individuals and line graphs show changes over time captures how these graphs are typically used. The other options misstate these functions—for example, bar graphs aren’t inherently about time trends, and line graphs aren’t limited to comparing individuals without a temporal element.