Dot Plot
Statistics & ProbabilityA 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. When the same value appears more than once, dots are stacked on top of each other.
Example
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. The stack of $3$ dots above $8$ shows it is the most common score.
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.
Definition
A dot plot (also called a strip chart or Cleveland dot plot) places one dot per observation along a numerical axis. Repeated values are stacked vertically. Dot plots preserve every data value (unlike histograms that bin data) and are ideal for small-to-medium datasets (up to about $50$ values).
Example
Daily steps walked by $15$ students: a dot plot reveals clusters around $5{,}000$ and $10{,}000$ steps, an outlier at $20{,}000$, and a gap between $12{,}000$ and $19{,}000$.
Key Insight
Dot plots are more informative than bar charts for small datasets because you see the full distribution, not just a summary bar. They are excellent for spotting outliers and distribution shape.
Definition
A dot plot provides a one-dimensional empirical distribution display. For large samples, overplotting becomes a problem; jittering (adding small random noise) or transparency help. Beeswarm plots are a variant that spreads points horizontally to avoid overlap while preserving the vertical axis scale.
Example
Comparing dot plots across multiple groups simultaneously (like boxplots) is done with a strip chart. Overlaying a box-and-whisker summary on the same axis creates a hybrid that shows both individual values and five-number summaries.
Key Insight
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.