The available number of openings shown on banner can be misleading for some of my classes (Cross Section and Bayesian) because this class has two sections that meet at the same time- one for undergraduates and one for graduates. Consequently, the number of available seats can show there is space, when in fact there is none.
Typically I have numerous students wanting a spot in these classes. Make sure this is the class for you. Goto the course websites listed above and look at the notes to get a feel for the level of rigor. Dropping the course sooner rather than later affords other students an opportunity to enroll. I will not support a change to an audit once you are registered in the course.
I do not maintain a waiting list. The few overrides I am able to grant tend to be
upperclassmen who are
econ/math double majors (for Cross Section and Bayesian)