With nine days left, massive polling error is Donald Trump's best shot to win

He has run out of time to truly turn things around

There are two major sources of error in handicapping the election. The first is the chance that the electoral environment changes between whatever day you’re making the forecast and election day. The second is the chance that the polls are so systematically biased toward one candidate that the other one pulls off a surprise victory (see: 2016).

With only…