How to read a chord diagram (and why we use them for sports records)
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Chord diagrams look like a tangle the first time you see one. Once you know what the arcs and ribbons mean, they become one of the quickest ways to see who dominated a team's history. This guide explains how they work, using our Los Angeles Lakers Legends print as a worked example. If you'd rather watch it build up step by step, try the interactive guide.
What is a chord diagram?
A chord diagram arranges groups around a circle and connects them with ribbons, the "chords". The width of each ribbon shows how big the connection is. Circular layouts like this were popularised in data visualisation by Circos, a tool Martin Krzywinski and colleagues published in 2009 for comparing genomes, and became widely used on the web through the chord layout in Mike Bostock's D3 JavaScript library. Today you'll see them used for migration between countries, trade flows and, in our case, sporting records.
How a SportsChord chord print is laid out
- Records across the top. Each coloured arc is one statistic. The Lakers print uses Assists, Points and Rebounds.
- Players around the base. Ten of the franchise's greats, ranked by their combined share of all three records, biggest first.
- One ribbon per player per record. Every player links to every record, so each name has three ribbons.
- Width is share. A ribbon's width is that player's share of the ten players' combined total for that record.
- Numbers for precision. On the Lakers print, each player's coloured band carries their actual totals.
A worked example: the Lakers' greats
Here are the numbers behind the print: regular-season career totals with the Lakers, from Basketball-Reference.
| Player | Points | Rebounds | Assists |
|---|---|---|---|
| Magic Johnson | 17,707 | 6,559 | 10,141 |
| Kobe Bryant | 33,643 | 7,047 | 6,306 |
| Elgin Baylor | 23,149 | 11,463 | 3,650 |
| Kareem Abdul-Jabbar | 24,176 | 10,279 | 3,652 |
| Jerry West | 25,192 | 5,366 | 6,238 |
| James Worthy | 16,320 | 4,708 | 2,791 |
| Shaquille O'Neal | 13,895 | 6,090 | 1,593 |
| Gail Goodrich | 13,044 | 2,081 | 2,863 |
| Byron Scott | 12,780 | 2,534 | 2,365 |
| Jamaal Wilkes | 10,601 | 3,119 | 1,474 |
A table makes you read every cell to spot the pattern. The chord diagram shows it straight away: Kobe Bryant's ribbon is the widest on the Points arc, Magic Johnson's dominates Assists and Elgin Baylor's leads Rebounds. Magic sits first around the base because his share is high across all three records, even though he doesn't top Points.
Tips for reading any chord diagram
- Start with the widest ribbon. It's the biggest single contribution in the chart.
- Read one arc at a time. Compare the ribbons leaving a single record before comparing across records.
- Look for balance. Similar-width ribbons mark an all-rounder; one dominant ribbon marks a specialist.
- Use the numbers for close calls. Classic research on graphical perception by Cleveland and McGill (1984) found that people judge position and length more accurately than angle and area, so where a print shows exact figures alongside the ribbons, use them to settle close comparisons.
Why we use them for sports
A team's history is really a web of connections between people and achievements. A league table or a list of records shows one statistic at a time; a chord diagram shows how a handful of legends shared out a franchise's biggest numbers, all at once. It's also the design that gave SportsChord its name.
Watch the interactive guide, browse all chord prints, or see the Los Angeles Lakers Legends print.