The Big Five personality classification (currently being discussed on the front page [1]) has been reproduced and has predictive power. Sure the results are 'mild' compared to the physical sciences, but it's the best (first?) result that's come out of psychology research that actually meets this bar so far. Apparently it was used by Cambridge Analytica during that whole FB scandal, which is not great but validates it at least?

CA was years ago. Google probably has a much more refined model by now. Too bad they aren't sharing it.

[1]: https://news.ycombinator.com/item?id=27097590

[2]: my comment on [1] https://news.ycombinator.com/item?id=27099032