the box plot

The middle half of the data sits in the box. It shows the spread, not how many.

What it leaves outThe box hides how many. Five values and five hundred draw the same box, and a gap in the middle of the data does not show at all.

2 · intermediate · cartesian · rung 2 · what’s reported

GAISE II · Level B p.45 · shipped on the platform · specBuilder.ts · native boxplot mark

Three worked examples

Which month was the most unpredictable?

Before you lookWrite down the month you think varied most from day to day. Not the busiest month — the least consistent one.

civicca_schools_poverty_and_tests.csv · 9,480 rows · 6 columns · 6 of the file’s 12 columns are on this page; the download has all of them

how many pupils met the state standard in mathematics, at every one of California's 9,480 schools, grouped by elementary, middle and high

What to look atThree boxes for nine and a half thousand schools. The box holds the middle half; it says nothing about HOW MANY schools are in it, and nothing about the one your own school sits in.

This example draws itself with a small script. With scripting off you can still read every word on this page, and the file itself is at data/ca_schools_poverty_and_tests.csv.

earth and spacehist_quake_magnitudes.csv · 2,508 rows · 1 columns · showing 400 of 2,508 rows on this page; the file has all of them

the magnitude of all 2,508 southern California earthquakes

What to look atOne box holding 2,508 earthquakes. It shows how spread out they are and tells you nothing about how many — that is the trade.

This example draws itself with a small script. With scripting off you can still read every word on this page, and the file itself is at data/hist_quake_magnitudes.csv.

teen healthnhis_teen_estimates.csv · 1,700 rows · 9 columns · showing 400 of 1,700 rows on this page; the file has all of them

every estimate, grouped by which breakdown it came from

What to look atA tall box means the groups inside that breakdown answered very differently from each other. That is where to look next.

This example draws itself with a small script. With scripting off you can still read every word on this page, and the file itself is at data/nhis_teen_estimates.csv.

the pool

Now build one yourself.

The pool opens with this file and this shape already drawn, so your first move is to change something rather than to start from nothing. Bring your own CSV if you have one. Nothing is uploaded anywhere — the chart is drawn in your browser, your work saves there, and it downloads as a picture or as a project file you can open again.

Open the pool → the box plot · ca_schools_poverty_and_tests.csv