It might be helpful check out the kinds of sources used by u/commiespaceinvader in this answer on how historians estimate the number of Jewish deaths in the Holocaust.

I think you need to far more specific regarding your subject. "Data" can refer to everything and anything. From casualties, economic outputs, trade, domestic life etc etc. The more specific you are the more you can move away from the implication that you are just looking for inconsistencies in established analysis. The vagueness of the question makes it appear (perhaps incorrectly) that you are here to reexamine the evidence for the Holocaust. Apologies if that is not your intention.