An exit poll just released by the Public Research Institute at San Francisco State University provided more good news for backers of the ranked-choice voting system used last month and slated for a rerun next year in contests for Treasurer and City Attorney.

The detailed survey of 2,847 voters from the seven supervisorial districts using RCV found that 61 percent preferred it to the old December runoff method, while only 13 percent preferred a traditional runoff. White and Asian-American voters understood the system best, according to the survey, while African-Americans and Latinos were less likely to understand it well.

Still, more than three quarters of voters of each ethnicity understood their ability to rank up to three candidates at least "fairly well." ... Voters who wanted to rank fewer than three choices persisted in doing so even after the voting machine spit back their ballot in 85 percent of the cases, and voters who had supported RCV before coming to the polls were much less likely to rank only one candidate than those who had opposed it (15 percent compared to 40 percent).

Voters with lower levels of education and income reported less understanding of the system, but overall, 87 percent of all San Franciscans polled said they had some understanding of the system.