Lumifer comments on If there was one element of statistical literacy that you could magically implant in every head, what would it be? - Less Wrong

3 Post author: enfascination 22 February 2016 07:53PM

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Comment author: Lumifer 23 February 2016 03:58:06PM 1 point [-]

So, you're taking the frequentist approach, the probability is the fraction of the times the event happened as n goes to infinity? But tomorrow is unique. It will never repeat again -- n is always equal to 1.

And, as mentioned in another reply, calibration and probability are different things.

Comment author: DanArmak 24 February 2016 02:40:23PM 0 points [-]

But tomorrow is unique. It will never repeat again -- n is always equal to 1.

The prediction is not unique. I group predictions (with some binning of similar-enough predictions), not days. Then if I've seen enough past predictions to be justified that they're well calibrated, I can use the predicted probability as my subjective probability (or a factor of it).

Comment author: Vaniver 24 February 2016 02:58:29PM 3 points [-]

The prediction is not unique.

The trouble with this approach is that it breaks down when we want to describe uncertain events that are unique. The question of who will win the 2016 presidential election is one that we still want to be able to describe with probabilities, even though it doesn't make great sense to aggregate probabilities across different presidential elections.

In order to explain what a single probability means, instead of what calibration means, you need to describe it as a measure of uncertainty. The three main 'correctness' questions then are 1) how well it corresponds to the actual future, 2) how well it corresponds to known clues at the time, and 3) how precisely I'm reporting it.

Comment author: DanArmak 24 February 2016 03:40:53PM *  0 points [-]

That's correct: my approach doesn't generalize to unique/rare events. The 'naive' or frequentist approach seems to work for weather predictions, and creates a simple intuition that's easier IMO to explain to laymen than more general approaches.

Comment author: Lumifer 24 February 2016 03:46:17PM 0 points [-]

this doesn't generalize.

What do you mean?

Comment author: DanArmak 24 February 2016 05:50:05PM *  0 points [-]

What Vaniver said: my approach breaks down for unique events. Edited for clarity.