In data visualization, which chart is best for showing distribution of a single variable?

• A. Bar chart
• B. Line chart
• C. Scatter plot
• D. Histogram

Answer: (D)

Understanding how values of a single numeric variable are spread across its range is the key idea here. A histogram does this by grouping data into bins (ranges) and showing how many observations fall into each bin. That setup makes the overall shape easy to read—where data clusters, whether the distribution is symmetric or skewed, how spread out it is, if there are multiple peaks, and where outliers lie at the tails. It’s the most direct way to assess distribution properties like normality, skewness, and modality for one variable.

Other charts serve different purposes. A bar chart compares counts or values across distinct categories rather than showing how a continuous variable is distributed across its values. A line chart emphasizes changes over an ordered domain, often time, highlighting trends rather than the full spread of values. A scatter plot reveals relationships between two numeric variables, not the distribution of a single variable.

So, a histogram best communicates the distribution of a single variable because it visualizes frequency across the variable’s range, making distribution features immediately apparent. Keep in mind that bin width matters: too many bins can look noisy, too few can hide important details.