Hillary Clinton’s chances of winning the presidency have held fairly steady in the FiveThirtyEight models over the past 10 days. The polls-only forecast currently gives her an 88 percent chance of winning; since Aug. 7, her chances according to that model have been between 83 percent and 89 percent. The polls-plus forecast puts Clinton’s chance of winning at 78 percent; over the past 10 days, her chances according to that model have been between 76 percent and 80 percent. Indeed, Clinton’s post-convention bounce has stuck around so long that Donald Trump has been reduced to tweeting out a poll that showed him close but still losing.
A lot of Democrats I know have started to talk as though this election is over. They point to the fact that no candidate since 1952 who was leading at this point in the election cycle, a few weeks after the conventions, has lost the popular vote. So if Clinton’s lead in the polls is clear and the polling leader at this point in the campaign has never lost, why aren’t Clinton’s chances of winning according to our models even higher?
There are a couple of answers.
Our polls-plus forecast looks at economic indicators, in addition to polls. The state of the economy has historically influenced the election, with a better economy helping the party holding the White House. The indicators we use — jobs (nonfarm payrolls), manufacturing (industrial production), income (real personal income) and others — currently show a decent but not great economy. The polls-plus model sees Clinton’s healthy lead in the polls and an economy that historically would presage a close election and so expects the race to tighten.
Our polls-only model looks only at the …