For AI agents: use /llms.txt for the Nakafa content index.
First decide whether the horizontal axis contains separate categories or intervals of one numerical quantity. That choice determines what each bar represents and whether bar width contributes to the frequency information.
Bar charts are used for categorical data (such as phone brands or favorite sports):
In the bar chart above:
Notice that each bar is separated from the others because they represent different categories.
Histograms, on the other hand, are used for numerical data grouped into intervals, such as time duration or height. The bars touch each other because the intervals of values are continuous.
These duration data contain observations. To avoid counting a class boundary twice, include the left endpoint and exclude the right endpoint, for example and . The final class includes . The variable is duration in hours.
The histogram above shows the following phone-use pattern among high school students:
Together, of the observations fall between per day, so this range contains the majority. The single most frequent interval is .
A histogram and a bar chart both use bars, but they answer different questions. The table compares what each chart requires from the data and how the bars are drawn.
| Difference | Histogram | Bar Chart |
|---|---|---|
| Type of data | Quantitative, grouped into intervals | Categorical, each bar for a single category |
| Bar shape | Bars touch each other, no gaps | Spaces between bars |
| Frequency display | For equal-width classes, height shows frequency. For unequal widths, area must represent frequency | Bar height shows quantity or proportion |
Use a histogram when:
Examples of data suitable for histograms:
A histogram shows which value intervals contain many or few observations. Comparing the bar heights or areas describes the distribution's shape, spread, and possible skewness. For separate categories without a natural numerical axis, use a bar chart.
Published: . Updated: .
