How unpredictable is the 2020 election?

Our poll aggregation partially pools toward a “fundamentals”-based election forecast. Elliott Morris summarizes:

What I did was create an index of economic growth over the past years using standardized percentages changes in 9 different variables (some of which you and Chris use in your LEI work). This gets combined with approval ratings, trial-heat polls and an interaction for polarization (what share of people tell the ANES they switched parties over the past 4 years) in a regression for the national forecast for Election Day.

Then I disaggregate those with a simple model based on how each state voted in the past few elections, plus the forecast national vote. The formula is literally state vote lean ~ lean in past cycle + lean in cycle 8 years ago + some home state effects + democratic national vote share. All interacted with polarization. Everything going back to 1972 here (1948 nationally).

Then we just random walk toward that prior, which implicitly puts more weight on the polls over time.

We fit our model to the available polls in 2012 and 2016 and it gave reasonable results.

Bob Erikson followed up with some skepticism:

For 2020 you can squeeze out enough info for the best model possible and then you run into a combination of Trump’s caustic history, a pandemic, a pandemic-induced economic catastrophe, BLM, then Trump’s response and the real fear that Trump will do what he can to sabotage an election he sees as likely to lose. Put another way, if the GOP candidate were a generic candidate like Bob Dole in his prime, you could be quite confident in your model’s predicted trajectory. With Trump….? I do not mean to bash forecasting in general or your model. And I do not necessarily expect Trump to pull a rabbit out of a hat; he is more likely to totally crash. But unlike in other elections, believing any model going forward, including even the model in my head, gives me the heeby jeebies.

Elliott replied:

I’m not so sure about that. Trump’s victory in 2016 matched the fundamentals dead-on. Our best prior is to expect the same to be true this time, +/- some error.

Further, polls should account for most of these whacky differences in how voters evaluate him (If indeed they do exist). The real potential problem that keeps me up is that the polls are just wrong again because of weighting, filtering, sampling issues etc that haven’t been fixed or have crept up since 2016.

Bob responded:

I will separate two arguments.

(1) I think models cannot infer the effect of the virus-induced economic disaster. It’s not the same as if it occurred as a natural result from dynamics of the economy (2008, 1929). So if the model were driven solely by the economy (the Economist’s model is not), I would not trust it much.

(2) I am a believer in understanding the forecasting power of trial-heat polls. So that does provide an anchor. I should not have left any impression otherwise. I do fret about an extra amount of variance in the polls that can result from here to election day. But then again campaign effects tend to be overrated and the polls have some remarkable stability.

And I remarked that most, if not all, elections are idiosyncratic in one way or another:

1948: first election without Roosevelt

1960: first Catholic candidate

1964: candidate abandoned by his own party

1968: first serious third-party candidate in a long time

1972: youth vote

1976: first major-party candidate in a long time who was an outsider

1980: Reagan was a scary unknown quantity

1992: volatile 3-candidate election

2000: seemed like a normal election but Gore should’ve won easily and he didn’t

2004: first election in a long time where foreign policy was a key issue

2008: first nonwhite candidate

2012: first Mormon candidate

2016: first female candidate, also Trump was an unusual candidate.

Is 2020 more unusual than all of these past elections? I don’t know.

And Chris Wlezien wrote:

One thing I wonder about is (possible) changes to how people vote and whether and how this matters for turnout and vote-counting, and polling.

Back in the old days when the Monkey Cage was a blog, we could’ve had this discussion there.