According to the Michigan instructions:
A Michigan Resident is an individual if you maintain a permanent home in Michigan. A permanent home is one in which you intend to return to.
A Michigan Nonresident is an individual who is neither a resident or part-year resident.
A Michigan Part-Year Resident is an individual that has moved into or out of Michigan during the tax year.
If a joint federal return is filed and one spouse is a resident of Michigan and the other is not, complete a Nonresident return and allocate the income on Worksheet 5.
For more information: