The Running Average Poll

The [WaPost] is publishing a daily, running average poll, from now until election day. The way it works is, every day, the poll by phone 350 people. On any given day, they give the percentage for Bush, Kerry, and Nader averaged over the past 3 days (1050 people), which has a margin of error of 3%. However, the values for the last 3 days are *correlated* (because the same vote go into producing numbers) -- but, a poll like this can reveal movements on >3 day timescales.