Belief and decision update

Record how your belief and your action changed from before to after, plus what uncertainty remains.

The mechanic quoted 1,400 dollars for the repair, you spent an evening researching, called a second shop, and got a quote of 950. You pick the second shop and move on. Two months later, facing another repair, you can't reconstruct what you learned. Was the first shop overpriced in general, or just on that job? How sure were you? The learning evaporated because it was never written down.

Belief and decision update is the move of recording, after evidence comes in, how your belief and your action changed from before to after, plus what uncertainty remains. The cue is the moment a probe resolves and you're tempted to just act and move on. The operation: note the before ("assumed the first quote was roughly fair"), the after ("their labor rate runs about 40 percent above area average, based on two comparisons"), the action change ("second shop for major work"), and the residual ("one data point; they may be competitive on routine service"). What changes is that each investigation compounds; next time starts from a recorded position instead of a vague memory. Skip the write-up for updates too small to ever matter again, like which checkout line was faster.