Three reasons why US presidential odds have tightened

Here the latest odds on betting sites for the Presidential election:

• PredictIt – tied
• Kalshi 55% Trump, 45% Harris (from as wide as 65-35)
• Polymarket 59% Trump, 41% Harris
• Betting sites around 58 Trump, 42% Harris

Now there should be some kind of arb there but I don’t think it’s wise, and definitely don’t do what this French guy who has put $30 million on Trump at Kalshi.

“Théo said he took an interest in U.S. polling data earlier this year. He observed that many polls underestimated Trump’s support in 2016 and 2020, and concluded that if Trump outperformed again this year, he would beat Harris. Théo also cited the “shy Trump voter effect”—the idea that people were reluctant to tell pollsters that they supported Trump.

“I know a lot of Americans who would vote for Trump without telling you that,” Théo said. Asked about changes that pollsters had made in their methodologies in an attempt to fix the problems of 2016 and 2020, Théo was dismissive, saying he had “not seen anything substantial.”

Théo sent dozens of emails to the Journal reporter over a two-week period. In many of them, he criticized polls from mainstream-media outlets that he saw as skewed in favor of Harris. On the Zoom call, he alleged that Democrat-aligned media organizations were laying the groundwork for social unrest by stoking expectations of a close race, instead of the Trump blowout that he anticipates.”

In any case, here are three reasons that betting odds have improved for Harris:

1) No one trusts polls

Like the above, many believe that Trump is being underestimated like he was in the past two elections. However Nate Silver makes a good argument here that the pendulum may have swung in the other direction.

“It’s hard to overstate how traumatic the 2016 and 2020 elections were for many pollsters. For some, another underestimate of Mr. Trump could be a major threat to their business and their livelihood. For the rest, their status and reputations are on the line. If they underestimate Mr. Trump a third straight time, how can their polls be trusted again? It is much safer, whether in terms of literal self-interest or purely psychologically, to find a close race than to gamble on a clear Harris victory.

At the same time, the 2016 and 2020 polling misfires shattered many pollsters’ confidence in their own methods and data. When their results come in very blue, they don’t believe it. And frankly, I share that same feeling: If our final Pennsylvania poll comes in at Harris +7, why would I believe it? As a result, pollsters are more willing to take steps to produce more Republican-leaning results.”

In addition, Silver made a compelling argument that the amount of clustering in polls in swing states is statistically impossible.

The takeaway here for any reasonable person is that nothing can be trusted until the votes are counted.

2) The early vote for women

The gender of early voters is only reported in Colorado, Georgia, Indiana, Michigan, North Carolina and Virginia but aggregated it looks like this.

Polls consistently show Harris far ahead of Trump among women.

In Michigan alone it’s 55%-45% for women. Now typically, it finishes in the 53-47%. That two percentage point swing — if it holds up through in-person voting, would tilt the balance. Now from what I’ve seen, females outnumbering men in mail-in voting isn’t unusual but the history of US mail-in voting is very short.

About half of Americans will vote by mail this year.

3) Voter enthusiasm

This chart from Gallup got some attention, as it shows Democrats more enthusiastic to vote for Harris than the were for Biden or even Obama.