<p>This might be a stupid question but
how hard is it to get into a top ranked department/lower ranked school but lower ranked department/top ranked school for Phd
For example, Harvard BME(ranked ~20) vs Georgia Tech BME(ranked2).</p>
<p>Well, both matter. Top-ranked departments will draw more highly-pedigreed applicants, than lower-ranked departments, and top-ranked schools will also see an increased number of highly-qualified applicants compared to lower-ranked schools. </p>
<p>The first effect should be obvious - if you want to be great in a given field, going to the “best” department will tend to be attractive. The second effect is a little less obvious and not as big, but it is still there. Some people need (or think they need, or just plain want) to attend a highly ranked school - perhaps it has always been a dream of theirs, or perhaps they aspire to something like finance or law where the school name carries more work, or perhaps they are an international student whose funding source cares only about school rank and not department rank.</p>
<p>But which will dominate depends a lot on the specific departments you are comparing. If you can find average GPA or GRE scores that should give you a pretty good idea, as GPA at least will often track with the difficulty of entry.</p>
<p>It really depends. In engineering, I would say the school ranked #1 tends to be the most selective, but after that, rankings are a little jumbled up.
In my field, aerospace engineering, caltech is by far the most selective school (it is ranked #1 with MIT). MIT is not as selective. I don’t remember who’s ranked #2, it might be Stanford. Princeton is ranked #9 or something, but it is more selective than any other school in the top 10 and is right behind Caltech (maybe even in front of MIT in terms of selectivity).
Public schools tend to be less selective despite being ranked higher than some of te private schools, mainly cause they’re usually a lot bigger</p>