On the STV procedure used, I’ve heard two stories. One is the Los Angeles Times article (see below). The other is from someone who claims to know someone at the accounting firm, who says they use fractional transfers. The Academy’s rules say only that “In the nominations voting, the marking and tabulation of all ballots shall be according to the preferential or weighted average system.” The way I read this, it allows the accounting firm to do all kinds of things, include “bottoms up” and various flavors of “multi-seat IRV”.

In my reading of newspaper article, it describes the random transfer method in which the randomization takes place before any ballots are counted. (Usually, this is done by shuffling them and then writing serial numbers on them in the randomized order.) Once a candidate reaches the threshold, you stop transferring more ballots to that candidate and start giving them to the next-ranked candidate on each one.

Another main variation on random transfers is the Cincinnati-Cambridge method, where you continue assigning votes to candidates who have already reached the threshold. After all ballots have been assigned, you calculate the fraction of the winner’s ballots that need to be transferred, 1/N, and then transfer every Nth ballot.