On first glance, someone who:
“maintains a permanent place of abode in this state and spends in the aggregate more than one hundred eighty-three days of the taxable year in this state” will be a (tax) resident."
However, there is an important exception as to when an even year-long abode is not considered of permanent nature:
7.1.3.2. A place of abode, whether in West Virginia or elsewhere, will not be deemed permanent if such abode is maintained only during a temporary stay for the accomplishment of a particular purpose.
(Section 110-21-7 - Resident And Nonresident Defined, W. Va. Code R. § 110-21-7 | Casetext Search + Citator)
Per example, an employee’s WV home that was only taken due to a long-term (but temporary) project assignment, doesn’t make that abode a “permanent” one.
So - in the case of your daughter, if she intends her permanent home to remain your home, and intends to only temporarily live in West Virginia most of the year, for the purposes of “accomplishing” her graduate studies, then it seems to me that she qualifies for that exception and is not required to treat WV as her “home stage” (at least for tax purposes).
And yes, not registering to vote in WV would be another important indicator.