The ever delightful blog "Math with Bad Drawings" is doing a series of posts on probability, and has just put one up that helps make base rate neglect vivid and concrete.

I can't bring myself to spoil the story (and I certainly can't do justice to the drawings), but I anticipate this is a post you'll want to share with family and friends. And I don't mind sharing part of the conclusions:

“So what have you learned?”


“Never make a decision blindfolded.”

The teacher laughed. “An impossible wish. We’re all wearing blindfolds, every moment of our lives, and they come off far less easily than this cheap piece of cloth.”

“Then what should we do, when we can’t take the blindfold off?”

“Do the best you can,” the teacher said, “and never forget that you’re wearing it.”

When we develop classes at CFAR, we tend not to use the word debiasing, since it's very hard to eliminate quirks of our ways of thinking. It turns out that a lot of what we do is learning to use your brain better, so you can reframe problems or use visual or verbal aids to help you spot the element that throws you and compensate.

Think of it as the cognitive equivalent of learning to walk on different surfaces when you have a trick knee.