inverted bell curve

In statistics, an inverted bell curve is a term used loosely or metaphorically to refer to a bimodal distribution that falls to a trough between two peaks, rather than (as in a standard bell curve) rising to a single peak and then falling off on both sides.E.g., see {{citation|journal=Journal of College Student Retention: Research, Theory & Practice|volume=16|issue=3|date=2014–2015|pages=307–324|title=Bimodal Inverted Bell Grade Distribution: Implications for Instruction and Student Retention|first1=Leah K.|last1=Gensheimer|first2=Charles T.|last2=Diebold|doi=10.2190/CS.16.3.a|s2cid=144272500}}.