Students' misbehaviour has/have worsened in the past few years.
Is it has or have? Or can both be correct with "has" referring to "misbehaviour" and "have" referring to students?
I'm inclined towards "has".
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.Sign up to join this community
Only has is correct:
Students' misbehaviour has worsened in the past few years.
"Students' misbehaviour" is a noun phrase. It refers to a type of misbehaviour: the noun "misbehaviour" is what is called the head of this noun phrase. In general, the type of agreement that a noun phrase takes is based on the type of noun that it has as a head. Noun phrases headed by the noun misbehaviour take singular agreement.
It is not grammatical to replace has with have in this sentence, even if you mean to refer to students.
"Misbehaviour" is also the head of the noun phrases "The misbehaviour of the students" and "The student's misbehaviour", so those would also take has:
The misbehaviour of the students has worsened in the past few years.
The student's misbehaviour has worsened in the past few years.