Here's a puzzle I like to give developers, because it's short, slightly uncomfortable, and teaches something you'll use for the rest of your career.

The puzzle: Over the next month, write down 20 predictions about your work. Each one gets a probability. "70% this PR merges by Friday." "90% the deploy goes out without a rollback." "40% the flaky test fails again today." At the end of the month, check which happened.

Now the question: when you said 90%, did 90% of those things happen?

If you've never done this, I'll make a forecast of my own: you're overconfident. Most people are. Developers are especially prone, because we estimate things constantly (story points, timelines, "this'll take five minutes") and rarely look back at the receipts.

What calibration actually means

Being calibrated means your confidence matches your hit rate. If you're perfectly calibrated, then across everything you labelled "70%," about 70% came true.

Notice that calibration is not the same as accuracy.…