Let’s discuss momentum. Nate Silver mostly dismisses it, but I don’t. And the election is in 17 days.
Yesterday, the Silver Bulletin election model flipped from Harris to Trump barely. That’s the first Trump lead since September 19.
Does Trump Have Momentum?
My answer is clearly. But Nate Silver mostly disagrees in his Q&A yesterday Does Trump Have Momentum?
To be open about my editorial thought process, it can be hard to know how much to emphasize these small shifts. Outside of major events like debates, the model typically does not move very much from day to day. And there’s no special significance to the 50-yard line. A change from 49.4 percent to 50.2 percent does not particularly matter more than one from 43.1 percent to 43.9 percent or 52.5 percent to 53.3 percent.
I agree with Silver on the difference on tiny shifts. But mercy, look at the cumulative shifts as shown in the lead chart.
Percentage Point Changes In the Last Month
- National: +8.5
- Michigan: +12.6
- Pennsylvania: +8.7
- Wisconsin: +8.9
Don’t worry Harris fans, this all happened with “tiny shifts”.
Silver continues …
The point is that most people tend to bet (literally in the case of prediction market traders) on trends continuing. If Trump has gone from 42 percent to 50 percent, in other words — already bad news for Harris — “momentum” implies that he’ll keep moving up: perhaps by Election Day, he’ll be at 60 percent, for instance. And that would be really bad news for Harris, the point where we could no longer honestly describe the race as a toss-up.
Once again, I disagree.
As in sports, momentum can change. So nothing implies Trump won’t put his foot in his mouth, or that Harris won’t have a disastrous interview.
But would you rather be in Trump’s shoes now or Kamila’s? As recently as a few days ago, Silver preferred Harris.
A good election forecast avoids momentum
The Silver Bulletin election forecasts are explicitly designed to be momentumless. In other words, the best prediction of what the forecast says tomorrow is what it says today; the technical term for this is that it avoids autocorrelation.
That is sort of reasonable. Overweighting the most recent polls too much leads to daily flip-flops on meaningless random changes.
But these changes are neither meaningless nor random. They are cumulative and reasonably consistent in direction.
Silver finally relented, after dismissing momentum for pages with …
The most important takeaways is are that 1) Trump has made real gains — at this point, we’re probably beyond the point where this can just be statistical noise but 2) you should be wary when you hear media talk about “momentum”: that he’s gained ground over the past two weeks does not necessarily imply that he’ll continue to do so.
I agree with both points emphatically, but momentum usually does not change unless there is an event. In football that might be an interception or a fumble. Now it could be anything, even something we don’t easily see.
Wisconsin Polls
Silver has Harris in the lead 50.5 to 49.5. One might look at that chart and be scratching their heads.
As I look it that chart I wonder about pollster bias. Rasmussen, for example is so consistently biased, that +2 for Trump might better be read as +1 for Harris.
But Emmerson College and Quinnipiac are little biased.
Today, I asked Silver to put in a link to his pollster ratings to better calculate.
I believe Silver errs in the opposite direction on recency. He goes back too far or back too far with too much weight.
Over time, and that might be weeks, Silver has slowly adjusted.
Chance of Winning Wisconsin
Those odds are well behind where they would be if Silver weighted recent polls more heavily, did not go back as far, or a bit of both as I prefer.
How Much of a Political Lagging Indicator is Nate Silver?
On October 12, I asked How Much of a Political Lagging Indicator is Nate Silver?
The answer, as you can see, is a lot.
This can be viewed as a feature or a bug, but Silver is slow to react.
Historical Momentum
I recall Silver’s 2008 election prediction. He got all 50 states correct and one of his reason was that all the polls were breaking the same way, in other words momentum.
But I got 49 of 50 states correct, in February, before Obama even won the nomination. I got Missouri wrong.
My rationale was that the economy would be so miserable by election time that every conceivable state would break for Obama.
One of my friends commented “What planet are you on to think Obama will win North Carolina?”
Why the Momentum Now?
To repeat my comment above “momentum usually does not change unless there is an event. In football that might be an interception or a fumble. Now it could be anything, even something we don’t easily see.”
That something most economists don’t see is the economy. For 67 percent of the nation (the asset holders and the home owners), the economy (the stock market) has been good to very good, offsetting inflation.
For the renters and struggling homeowners fed up with property insurance, food, and other inflation, the economy borders on miserable.
Who is that? Young voters, blacks, and those without a college education.
You can see that in the polls.
Harris is still ahead in those groups, but in percentage point gains and losses, Trump has made historic inroads.
I propose the remaining undecided voters are breaking as I suggested in February.
I repeated that message in April with People Who Rent Will Decide the 2024 Presidential Election and again on June 19 in Why Angry Renters Will Decide the Election, Take II
Economists say wages are now rising faster than the CPI. That’s not true for those who rent or wish to buy a house.
Trump fell way behind after a disastrous debate with Harris. That momentum ended a month ago.
People are again asking “Am I better off than 4 years ago?”
If you own stocks or refinanced your house at 3.0 percent, you likely are better off. And that’s a big majority. But that’s not who will decide the election. And it is a big part of why Harris is struggling.
Trump, not Harris is the candidate of change.