In 1870, Chicago contained twice as many Canadians as Dublin, the same number of Arabs in Berlin, half as many Italians as Naples, and two and one-half times the Jewish population of Istanbul. Which graph type is best to express this information?

• A. Map
• B. Line graph
• C. Pie graph
• D. Bar graph

Answer: (D)

When you need to compare amounts across several separate groups, a bar graph is the most effective option. Here you’re looking at different populations (Canadians in Chicago and Dublin, Arabs in Berlin, Italians in Naples, and Jews in Istanbul) and how their numbers stack up against one another. A bar graph uses the length or height of bars to represent each quantity, so you can quickly see which city-group is larger, smaller, or how they relate in ratio (for example, one bar twice as tall as another). This visual makes the comparisons clear at a glance and handles multiple categories in one view.

Other graphs aren’t as suitable here. A map would emphasize geographic location rather than the exact quantities. A line graph implies a continuous change over time, which isn’t the focus of these static counts. A pie chart would try to show parts of a single whole, which doesn’t fit when you’re comparing several distinct quantities across different groups. A bar graph keeps the focus on the magnitudes you’re comparing.