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Yesterday, Hillary Clinton’s PEC win probability hit 95%.

In last night’s debate, the 2005 candid video of Donald Trump saying what he does with women was still on everyone’s mind. In response, he brought up many topics beloved by Republican rank-and-file voters: Bill Clinton, Benghazi, emails…it was a veritable Greatest Hits of 1996-2016. The likely consequence of this scorched-earth strategy is that Republican leaders are trapped. All their base (R) belong to Trump. This will reverberate downticket.

This seems like a good time to reveal one of the Princeton Election Consortium’s own secrets. Thankfully, it does not involve an Access Hollywood video.

Here it is: poll-based Presidential prediction is not very hard.

I guess that is a pretty boring secret. Sorry.

It is an interesting irony that poll aggregation got popular in 2008, a year when there was not that much suspense in the Presidential race. That year, Barack Obama led John McCain for almost the entire campaign season, with the possible exception of the week after the Republican Convention, where Sarah Palin stole the show. That ended up with a 7-percentage-point popular win, and an electoral outcome of 365-173.

President Obama’s re-election in 2012 carried even less suspense: he never lost the lead to Romney. The closest he came was right after the first debate, though even then he was slightly ahead. The eventual outcome was a 4-percentage-point popular win and an electoral outcome of 332-206.

I have formed a sneaking suspicion that the runaway success of poll-based forecasting arises from these two victories. If this is correct, then quantitative prediction models at sites like The Upshot and FiveThirtyEight (and PEC) basically serve as prurient entertainment for progressives. Which is okay with me. Everyone needs an outlet. Republicans got theirs in 2010 and 2014.

I think it is a good thing that the other sites did not start in 2004. When many hobbyists (including electoral-vote.com, me, and many others) started doing poll aggregation, it was a tough year: John Kerry and President George W. Bush traded the lead several times, and it was a photo finish, coming down to Ohio. When it comes to probability, it is too easy to do a suboptimal job of extracting all the possible value out of polls. That would have led to a boring year of commentary: “it’s too close to call!” seems okay for a pundit to say, but is that what we really want from a data nerd?

This year, Hillary Clinton’s lead has been remarkably consistent, despite the emotional drama offered by commentators. At some level the drama is justified by the expected value, which is defined as the size of a payoff (or cost) multiplied by its probability. This year, the cost of a presidency as profoundly disruptive as Trump’s would be enormous. Even 5% of that would be notable.

Reader Damien asks wonders if “one candidate leading an ‘open seat’ presidential race from wire-to-wire is almost unprecedented.” The answer is that we haven’t seen anything like it in over 60 years. The comparisons are 1952 (Eisenhower v. Stevenson), 1960 (Kennedy v. Nixon), 1968 (Nixon v. Humphrey), 1988 (G.H.W. Bush v. Dukakis), 2000 (G.W. Bush v. Gore), and 2008 (Obama v. McCain). Of these, the only race where one candidate led consistently from start to finish was Dwight Eisenhower, who eventually won by 11 percentage points (electoral outcome, 442-89).

Statistically, the two most notable features of this year’s Presidential race have been its closeness and its stability. The stability arises from polarization, in which opinion has been nearly immovable. The Meta-Margin has averaged Clinton +3.6% with a standard deviation of 1.0%. Clinton’s lead is 3.5 standard deviations, which is really big, statistically speaking. It’s a core reason why the PEC win probability has been so stable.

If the Meta-Margin were to drift as high as Clinton +6.0%, it would still be within two standard deviations of the average. Then again, the last week has been pretty surprising. If that happens, we can drill into why, as well as talk about how it affects the Senate and House.

That is not to say that prediction is perfect. I certainly learned some strongly administered lessons in 2004 and 2014. But Presidential analysis seems to be a problem that is well under control, thanks to the abundance of data and analysis from hordes of nerds.

In coming weeks I will get into the remaining puzzles of this year, such as how our approach differs that of other sites, and what it would take for Democrats to re-take the House. Other commentary is likely to concern one of the following topics:

Downticket (where you should get involved!),

Senate/House prediction and analysis,

Partisan polarization, and

Making fun of pundits.

These are more in the domain of “data journalism,” which reader NFB points out is a big source of added value. Still, the horserace coverage is what initially draws people in.

Did I mention that you should get involved downticket? Explore the links in the High-Impact Races sidebar on the left.