I'm skeptical of the Jewish statistics, which are allegedly based on Hillel documents.

Is Harvard really 25% Jewish? Or is that the fraction of domestic students who have some (possibly small) Jewish ancestry?

And what's the source that Caltech is 5.5% Jewish? Could that mean 5.5% are actually practicing?

Did Hillel actually perform a serious survey/study in these schools, or are these numbers based on some student's guess?

Admittedly, I haven't looked through his citations and supporting material, which looks pretty extensive.