the matrix

Colour carries the value, not position. The diagonal is always strongest — that is a thing compared with itself.

What it leaves outColour is read by eye and eyes are bad at it. Two cells a shade apart look equal, and the order of the rows decides which blocks appear.

2 · intermediate · rung 3 · what’s related

shipped on the platform · corr · heat

Three worked examples

Which two of these move together?

Before you lookWrite down the pair you expect to be most strongly related.

civicca_school_poverty_and_college.csv · 1,968 rows · 16 columns

every California high school on four measures: poverty, college-going, and how many eleventh-graders met the state standard in English and in mathematics

What to look atRead the diagonal first and then ignore it -- a thing against itself is always +1.00 and means nothing. Then find the two darkest cells off it. The measures move together, and none of them is the cause of another.

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 spacecorrelation_co2_temperature_exoplanets.csv · 33 rows · 4 columns

carbon dioxide, global temperature and planet discoveries, year by year

What to look atCompare each column with every other. The diagonal is always strongest — that is a thing compared with itself, and it means nothing.

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/correlation_co2_temperature_exoplanets.csv.

teen healthnhis_teen_group_profiles.csv · 29 rows · 12 columns

ten teen-health measures, every pair compared

What to look atColour is the strength of the relationship. The diagonal is perfect and means nothing, because that is a measure compared with itself.

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 matrix · ca_school_poverty_and_college.csv