My Correlation Is Causation Because My P Is Wee

Class 63

It would be a good joke to conclude “If Pr(Data we didn’t see | Cause false) is small then Cause is true”, but it isn’t. People believe it. Peers review it. It is a bad idea that refuses to die. You cannot, you simply cannot, talk people out of it.

Video

Links: YouTube * Twitter – X * Rumble * Bitchute * Class Page * Jaynes Book * Uncertainty

HOMEWORK: Given below; see end of lecture.

Lecture

This and next week wrap up the majestic anti-P-value rant.

I have seen comments, here, and, yes, there, with attempts to justify P-values. This is natural. People do not want to give up on their magic tool. Yet give it up they must.

But what I haven’t seen, not anywhere, was anybody making any comment on this:

Pr(What we want to know | All evidence considered).

This is just ignored and the Wee P White Knights charge the field with their itty bitty poles (the weer the better) and offer any and all manner of arguments to save the mighty P.

The P-value, again, is this calculation:

P = Pr(What did not happen | Cause is false)

Or if you don’t like “Cause is false”, then write “null is true”. The “null” is that the cause you think was present, wasn’t.

There is no sound valid or sober logical argument that leads from “My P is wee, therefore ‘Cause is false’ is false”. Which is a long-winded way of saying “My P is wee, therefore Cause is true”. Replace that by ‘Cause is likely true’ or whatever, and it is still a fallacy.

Why, why, why—I’m asking why—do people think they can get at “What we want to know” from “What did not happen”? Why not just go right for “What we want to know”?

No, I’m asking.

I am lost for how to talk people out of P-values. I welcome all ideas.

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