New FiveThirtyEight Forecast Not as Certain as It Appears

Posted: Aug 13, 2020 3:00 PM
New FiveThirtyEight Forecast Not as Certain as It Appears

Source: (AP Photo/Charlie Riedel)

FiveThirtyEight updated its 2020 election forecast yesterday, projecting a 71 percent chance of a Biden presidency as of August 12. On average, according to simulations run against FiveThirtyEight's prediction model, Biden received 323 Electoral College votes and 53 percent of the popular vote. Trump, on the other hand, garnered only 215 Electoral College votes and 46 percent of the popular vote.

Plenty of time remains until the election to introduce unexpected externalities that significantly impact the outcome of the election, the website acknowledges. But while the 2016 model fluctuated three times between wide and narrow margins for a Clinton win, this year's has proved relatively stable. 

"The forecast shows Trump with a meaningful chance of winning because there’s still plenty of time for the race to tighten," according to the forecast's main page

FiveThirtyEight proceeds to reassure polling skeptics:

"But wait! Should you even trust the polls? Hillary Clinton led in the polls in 2016, right? Yes. But Clinton had only a small advantage in most surveys — Trump’s win was well within the range of normal polling error."

Except that FiveThirtyEight gave Trump almost the exact same odds four years ago. Their 2016 election forecast projected that Democratic nominee Hillary Clinton would surpass Trump on election day with a 71 percent chance of winning, the same odds Biden enjoys now.  On August 12, that number was even more extreme at almost 88 percent. Clinton had 302 electoral votes and 48.5 percent of the popular vote, not a small advantage. 

FiveThirtyEight editor Nate Silver published a commentary on the forecast entitled, "It's Way Too Soon to Count Trump Out." He explained that one factor in Trump's 2016 outlook was the relatively inconsequential polling disparity between him and Clinton, while this year's polls indicate a much more reliable Biden lead.

"The uncertainty in our current 2020 forecast, conversely, stems mostly from the fact that there’s still a long way to go until the election," Silver writes. "Take what happens if we lie to our model and tell it that the election is going to be held today. It spits out that Biden has a 93 percent chance of winning. In other words, a Trump victory would require a much bigger polling error than what we saw in 2016."

On August 12, 2016, the "Now-cast," or what the election outcome would be if it occurred on the day of forecasting, gave Clinton an 89 percent chance of winning. 

Silver neglects to mention that point, although he does note that Trump has a 10 percent chance of winning the Electoral College despite losing the popular vote, which is exactly what happened in 2016.

"Biden is in a reasonably strong position: Having a 70-ish percent chance of beating an incumbent in early August before any conventions or debates is far better than the position that most challengers find themselves in," concludes Silver. "...But for the time being, the data does not justify substantially more confidence than that."