[marcosdumay]

> with no actual change in the underlying data or method

Proving a known hypothesis or deciding what you want to know after the fact are completely different methods.

> Did you cast some ancient spell when you came up with the hypothesis or something?

"I'll know it when I see it" is an incredibly vague way of doing science that requires extra rigor somewhere else to compensate.

Or, in a maybe better explanation, testing for multiple hypothesis is subject to this kind of failure:

https://xkcd.com/882/

So you need more data confirming your theory.

But if you state your single hypothesis beforehand, you are at the situation of the top square, with a high-confidence result.