How does pref ranking work

It is just the same as the other invited rounds, the sororities are doing the choosing. They submit their own ranked lists of pnm's to invite back, and they never see how the pnm's rank them so that's not a consideration in their decision making.

Every round, each chapter is given a limit on the number of pnm's they can invite back, just like pnm's are given a limit of the houses they can visit. If you are ranked high enough before a house's cutoff number you will be on their invitation list, and if not you will be released. This is why you shouldn't take cuts personally, you could have been just below their cutoff and they liked you fine but they can only have back so many.

Your ranks of the chapters come into play when more houses want to invite you back than you can have for the round. That's when your lowest ranked houses drop off and you go back to the ones you have left.

On the chapter side when pnm's drop them, other pnm's are pulled up from a flex list they have so they can get as many back as possible.

All rankings, pnm's and chapters', are fed into a computer and an algorithm sorts it out and generates the final attendance lists for each pnm and each chapter.

Pref is a little different because there are no drops after pref, only bid matching. Every pnm a sorority invites to pref is on their bid list somewhere. If you are asked to pref it is because that house can see you as a sister.