Advantages and Disadvantages of Different Graphs

The same data can look very different depending on which graph you use. Picking the right type is not about decoration — each graph makes a different kind of comparison easy to see, and the wrong choice can hide the pattern you actually want a reader to notice.

A bar graph is best when you are comparing separate categories against each other, like the sales of five different products. The advantage is that differences in bar height are easy to judge at a glance. The disadvantage is that a bar graph says nothing about how a value changes over time.

A line graph is best when you are tracking a value as it changes, like temperature over a week. The advantage is that trends, increases, and decreases are immediately visible. The disadvantage is that a line graph can be misread if the data points are not evenly spaced.

A pie chart is best when you want to show how a total is split into parts, like a class survey of favorite subjects. The advantage is that the reader instantly sees which part is largest. The disadvantage is that pie charts become hard to read once there are more than five or six slices, since the small slices are difficult to compare.

Ask what question the graph should answer. "How do these groups compare?" points to a bar graph. "How did this change over time?" points to a line graph. "What share does each part make up?" points to a pie chart. Reading the graph correctly also means learning to spot a poor choice — see misleading graphs for how a graph can distort the data it displays, and critiquing data presentation for a checklist to evaluate any graph you see.

Related lessons

• Statistics