Tree diagrams

Not the sole province of mathematics, tree diagrams go as far back as 1296 and have been used to organise information in every field of knowledge.

What they do have in common is a hierarchy and branches, but they can be rotated and tilted depending on the user and the purpose.

I was going to sketch up another example, but I thought I’d just borrow them from Creative Commons and square them up, and had a wealth of learning. Bits will be missing because, just like living trees, tree diagrams are rarely square.

From top left to right, we have Darwin’s tree of life 1859, a syntax tree, a family tree template, Phylogenetic tree of Theropods respiratory system, Haeckel’s foundations of science tree 1866, and one and a half medieval trees of knowledge.

But it can’t finish there, can it? I must include the famous Monty Hall Problem – that a contestant in a game show is presented with 3 doors, behind one of which is a great prize and the others have goats, or nothing. The contestant picks a door. The host reveals what is behind another door, which is (predictably) a goat. Two doors remain and the contestant is asked if they want to change their mind.

This tree looks at the probability of whether the contestant should switch.

If you’re having trouble reading it, and ever find yourself as the contestant – switch.

I’ll return to the more predictable trees in future – 100%, despite stem-and-leaf plots calling and data needing truncation.

For more tree squares, go to Becky’s challenge.


  1. Well I like your divergence into this different trees, even if they made my head swim a bit. You’ll be happy to hear that the state of Hawaii is actually giving away goats as they seek to reduce the population in the vicinity of one of the parks. I hope that doesn’t mess up your Monty Hall Problem!


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