AP Statistics · Lesson 7 of 15 · Unit 1
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Five-number summaries and boxplots give you a fast, visual breakdown of a distribution’s quarters, outliers, and skewness. On the AP Statistics exam, you will read and compare boxplots in Section I multiple-choice questions, and you may need to interpret five-number summaries and mean-versus-median relationships in Section II free-response questions.
In the digital Bluebook exam, you will not draw boxplots by hand, but you must be ready to:
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The five-number summary divides an ordered quantitative dataset into four groups containing approximately equal counts of data ( each):
A boxplot (often called a modified boxplot) displays the five-number summary graphically while flagging outliers using the rule:
Any observation strictly below the lower fence or strictly above the upper fence is an outlier and is plotted as an individual point (dot or asterisk).
| Boxplot feature | Where it is drawn | Share of the data |
|---|---|---|
| Left (lower) whisker | From the smallest non-outlier value in the dataset to | About (including any low outliers) |
| Left half of box | From to the median | About |
| Right half of box | From the median to | About |
| Right (upper) whisker | From to the largest non-outlier value in the dataset | About (including any high outliers) |
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