One unique thing I find about graduate schools in the US is that PhD schools are also open to those who have only completed their bachelors. Where I'm from, completing masters is an absolute prerequisite before pursuing PhD. My question is, do these PhD students who only have completed their bachelors make up the majority of the PhD students, a.k.a are they the 'default'? Or is it masters degree holders? Thanks in advance!
(Sorry for my bad english)