what decides rank

After four years in the greek system at UVA I'd have to say the biggest factor is what type of guys each fraternity attracts. You find that people with similar personalities compete for the same frats and the frats in the same tier compete for similar new members. What decides the order of those tier is somewhat populairty based. There are frats with bigger houses, more money, that go harder than others. Other frats maybe don't throw parties as often or don't care as much about their image. Sorities are of course a huge factor. Certain sorities match up with certain fraternities which tend to solidify the tier system on both sides. In my oponion PNMs will always benefit from not looking at greek rank to make a choice but during the school year and rush exploring multiple houses no matter what tier people say they are in. You don't want to join a fraternity based on popularity and later end up regretting the fact because their personalties are differnt.

Looks, personality, attendance at parties, money/connections, and history. By history I simply mean people are reluctant to move sororities/fraternities that have been historically top down in ranking and move other ones up. People expect them to stay at the top, and it's kind of self-fulfilling prophecy. Change occurs, but very very slow.y