Visualization VocabularyDataviz vocabulary
Diagram: notched box plot
Drawing: Adrien Taudière (CC0)
ggplot2 example: notched box plot
Adrien Taudière (CC0); R code ↓; data: Michelson 1882, via HistData (Friendly et al. 2026) (GPL)

chart

notched box plot

Box hollowed by a notch showing the uncertainty around the median.

boîte à moustaches à encoches

Boîte creusée d'une encoche figurant l'incertitude sur la médiane.

Deux encoches qui ne se recouvrent pas suggèrent des médianes différentes. Vérifié : options notch et varwidth de geom_boxplot() documentées dans Data Visualization: A Practical Introduction (Healy).

Classification

  • chart
  • boxes and densities › boxes
  • distribution
  • the name evokes: object

Channels

  • position on common scale; main: median, quartiles, confidence interval of the median (the notch)
  • length; secondary: interquartile range
  • area; secondary: interquartile range (the area can sometimes depend on the number of points)
  • spatial region; main: group
  • color hue; secondary: group

Attestation

Scientific literature

OpenAlex: 20 papers since 1997, 30% in the last five years; mostly in Biochemistry, Genetics and Molecular Biology, Medicine, Computer Science

Seminal references

R packages

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(tidyr)
library(HistData)

## Stigler's five sets of 20 measurements, in the order Michelson made them.
sets <- as_tibble(MichelsonSets) |>
  pivot_longer(everything(), names_to = "set", values_to = "velocity") |>
  mutate(set = factor(set, labels = paste("Set", 1:5)), speed = velocity + 299000)

p <- ggplot(sets, aes(x = set, y = speed)) +
  geom_hline(yintercept = 299734.5, colour = "#9b2367", linewidth = 0.5) +
  geom_boxplot(notch = TRUE, width = 0.55, fill = "#e4e4e4", colour = "#535353",
               outlier.size = 1.2) +
  annotate("text", x = 3, y = 299734.5, label = "Today's value, in air", colour = "#9b2367",
           hjust = 0.5, vjust = 1.4, size = 3.2) +
  scale_y_continuous(labels = lex_number, breaks = lex_break_breaks, expand = lex_break_expand) +
  labs(title = "The five medians agree, and all lie above today's value",
       subtitle = "Michelson's 1879 measurements, five sets of 20; the notch shows the median's uncertainty",
       x = NULL, y = "Speed of light (km/s)",
       caption = "Data: Michelson 1882, via the HistData R package") +
  theme_lex_viz(grid = "y", arrows = "y", break_not_zero = "y")

Sources (1)

Cite this entry

Stable addresshttps://dataviz.adrientaudiere.com/en/term/notched-box-plot.html

ReferenceTaudière Adrien. 2026. notched box plot. In Visualization Vocabulary, version 1.0.0. IdEst. https://dataviz.adrientaudiere.com/en/term/notched-box-plot.html

BibTeX
@incollection{taudiere2026-notched-box-plot,
  author    = {Taudière, Adrien},
  title     = {notched box plot},
  booktitle = {Visualization Vocabulary},
  year      = {2026},
  version   = {1.0.0},
  publisher = {IdEst},
  url       = {https://dataviz.adrientaudiere.com/en/term/notched-box-plot.html},
  note      = {CC0 1.0}
}

Page created on 2026-10-13. Text last changed on 2026-10-22. Images last changed on 2026-11-12. Numbers computed on 2026-10-22.