Define a histogram and its use.

• A. To display the distribution of a continuous variable using bars; shows the shape.
• B. A histogram summarizes data using a line.
• C. A histogram shows the relationship between two variables.
• D. A histogram is used to display boxplot data.

Answer: (A)

A histogram is a graphic that displays the distribution of a single continuous variable by grouping data into consecutive intervals (bins) and drawing a bar for each interval. The height of each bar represents how many observations fall into that interval (or the proportion if you use density). Bars are usually touching to indicate the data are continuous. This visualization lets you see the overall shape of the data: whether the distribution is roughly symmetric or skewed, whether it has one peak or multiple (unimodal vs. bimodal), and how spread out the values are. It also helps you spot outliers or gaps. It’s not used to show the relationship between two variables (that would be a scatter plot or similar) and it doesn’t display boxplot data (that’s a box plot).