# Confidence for a human answer

`confidence = 1 − (max(gut, head, final) − min(gut, head, final)) / 10`

If the reads agree, confidence is high. If the gut said 3 and the final said 8, confidence is 0.5.

For a `pick`, the person sets a "how sure" thumb after choosing, and confidence is that value divided by 10. A felt single sweep has no spread, so confidence is `null`; treat null as "unknown", never as certain.