What it shows
A dot plot of the kind used to show a distribution. Each of 30 students reported their hours of sleep the night before an exam, to the nearest hour, and each student is one dot stacked above that value.
Because every observation is visible, the plot shows the shape of the data and the count at each value at the same time. The data are illustrative.
How to read it
Count the dots in a column for the number of students at that value: 9 at 7 hours, the most common answer.
The values run from 4 hours to 10 hours, with a single student at each end.
The distribution is roughly symmetric around 7 hours, with slightly more students above it than below.
The numbers behind it
- Counts: 4 hours, 1; 5 hours, 3; 6 hours, 6; 7 hours, 9; 8 hours, 7; 9 hours, 3; 10 hours, 1.
- n = 30, reported to the nearest hour.
Ways to use it in teaching
Collect the class’s own sleep hours and build a dot plot on the board, then compare it with this one.
Students can read the mode, median and range straight from the dots.
As a short exercise, convert the plot into a frequency table and back.
For the summary statistics behind this kind of chart, see our plain-language guide to descriptive statistics.
Sources
- Çetinkaya-Rundel, M., & Hardin, J. (2024). Introduction to modern statistics (2nd ed.). OpenIntro. https://openintro-ims.netlify.app/
- Dot plot (statistics). (n.d.). In Wikipedia. Retrieved October 18, 2026, from https://en.wikipedia.org/wiki/Dot_plot_(statistics)
