Below are figures on PhDs earned in the physical sciences by graduates of these 3 colleges from 2005-2014.
55 … College of Wooster
20 … Muhlenberg
14 … Clark
Source: https://ncsesdata.nsf.gov/webcaspar/OlapBuilder
That’s a fairly big difference, although it’s not entirely clear what it signifies.
Wooster may be attracting a different kind of student than the other 2 schools (for whatever reason).
More physics majors at Muhlenberg and Clark may be choosing to attend med school.
Or, Wooster may be attracting similar students but doing a better job at motivating and preparing them for grad school.
Here is Wooster’s profile on the “Colleges That Change Lives” site:
http://ctcl.org/college-of-wooster/
Wooster’s apparent emphasis on research opportunities and independent study may help account for its higher PhD production.