It means that out of state applicants need better stats than in state applicants in order to be considered for an interview (it's essentially like the in-staters are being graded on a curve).
Going through the posts from last years NAU cycle, the stats for those invited to an interview were:
Out of state - cGPA: 3.75, GRE: 157V, 156Q, 4.5AW
In the state - cGPA: 3.59, GRE:155V, 153Q, 4.1AW
As you can see, there's a lower average for the in-state interviewees, particularly in overall GPA