This reminds me of the statistic that men are on average taller than women. This is actually a useful heuristic for making policy at a mass scale. It is worse

This reminds me of the statistic that men are on average taller than women. This is actually a useful heuristic for making policy at a mass scale. It is worse than useless as a way of estimating the height of someone you just met. The actual experience should completely invalidate any priors, which are trivially insignificant at the individual level.