It’s satstics applied to cultural anthropology in its current form, it doesn’t have a hard underpinning and changes from culture to culture. So it’s just relative opinions most of the time.

No idea, I didn't study that but I'm sure they are very transparent when referencing external sources or when generating new knowledge. Speaking about history, already when browsing a source like Wikipedia it becomes quickly apparent which things actually happened e.g. like when the UN was founded and things which are difficult to see like for instance what happened with JFK.

Also it seems mysterious to me how to apply statistics in this, especially speaking about definition of probability and applying it to seems that actually happened or not - in contrast to future events or thought experiments.