the scatter

Each dot is one thing measured twice. A tight cloud along a line means the two move together.

What it leaves outTwo things moving together is not one causing the other, and a third thing neither axis shows may be moving both.

2 · intermediate · cartesian · rung 3 · what’s related

GAISE II · shipped on the platform · scatter

Three worked examples

Do crowded places have worse air?

Before you lookWrite down yes or no, and what you would expect the cloud of dots to look like.

civicca_school_poverty_and_college.csv · 1,968 rows · 16 columns

every California high school: how many of its students qualify for a free lunch, against how many went on to college

What to look atThe seven yellow dots are Whittier Union, and one of them is this school. Now stop reading the slope and read the SPREAD: at any poverty you pick, schools run from under 40 per cent to over 90. The line is not a prediction about anybody.

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_school_poverty_and_college.csv.

earth and spacevoid_exoplanet_mass_period.csv · 5,981 rows · 3 columns · showing 400 of 5,981 rows on this page; the file has all of them

5,981 planets outside our solar system: how long their year is, and how heavy

What to look atLook at the EMPTY parts. The gaps are where our telescopes cannot see, not where planets are absent. Both axes step by powers of ten — each gridline is ten times the one before.

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/void_exoplanet_mass_period.csv.

teen healthnhis_teen_group_profiles.csv · 29 rows · 12 columns

twenty-nine groups of teens, each measured on anxiety and on depression

What to look atEach dot is one group measured twice. They rise together, which does not mean one causes the other, and both may follow something neither column names.

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_group_profiles.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 scatter · ca_school_poverty_and_college.csv