Dot Plot
A dot plot displays each data value as a dot above a number line, making it easy to see the distribution of a small dataset.
Definition
A dot plot shows each piece of data as a dot on a number line, with dots stacked on top of each other when the same value appears more than once. Also called a strip chart or Cleveland dot plot, it places one dot per observation along a numerical axis, preserving every data value (unlike histograms that bin data) and is ideal for small-to-medium datasets (up to about $50$ values). Formally, a dot plot provides a one-dimensional empirical distribution display; for large samples, overplotting becomes a problem, so jittering (adding small random noise) or transparency help, and beeswarm plots are a variant that spreads points horizontally to avoid overlap while preserving the vertical axis scale.
Example
For quiz scores $7$, $8$, $8$, $9$, $7$, $10$, $8$, a dot plot places dots above $7$, $8$, $8$, $8$, $9$, $10$ on a number line, and the stack of $3$ dots above $8$ shows it is the most common score. Daily steps walked by $15$ students might reveal clusters around $5{,}000$ and $10{,}000$ steps, an outlier at $20{,}000$, and a gap between $12{,}000$ and $19{,}000$. Overlaying a box-and-whisker summary on the same axis creates a hybrid that shows both individual values and five-number summaries.
Key Insight
Dot plots show every single data value, making them great for small datasets: you can see the shape, spread, and any unusual values right away, and they are more informative than bar charts for small datasets because you see the full distribution, not just a summary bar. Cleveland's dot plots (distinct from data dot plots) are line-up charts that compare numerical values across categories more accurately than bar graphs, exploiting the perceptual advantage of position on a common scale.