The data scientist who called Trump’s 2024 win now gives Democrats a 78% shot at the Senate

Thomas Miller, a data scientist at Northwestern University, predicted in 2021 that Democrats Jon Ossoff and Raphael Warnock would win the Georgia Senate runoffs. This proved accurate, and Miller's methods gained credibility when he applied them to the 2024 presidential race, projecting a Trump victory. Miller's approach involves starting with the top prediction markets at the time and adjusting for site-specific biases using proprietary algorithms.

For the 2024 elections, he updated his odds every 10 minutes on a continuously updating band. Now, Miller has turned his attention to the 2024 Senate elections, calculating the percentage chance that each of the 35 contested seats will go blue or red in real-time. He begins with betting odds from Kalshi and Polymarket, making statistical adjustments to convert them into probabilities.

Miller then applies multiple time series analysis to identify "underlying factors" that account for 80% to 90% of the changes in probabilities. He believes that Donald Trump's actions and words significantly impact all races, as voters' reactions to his statements influence the entire market. Miller launched his "NowCasts" on October 22 and began applying his methodology on September 19.

From September 19 to October 23, the probability of Republicans retaining control of the Senate fell from 36% to 22.5%. Currently, Democrats lead the odds in 18 of 35 races, and if these odds hold, they could secure 18 of 35 seats, shifting the Senate majority from Republican 53 to Democrat 52. Miller notes that the odds are highly volatile and could change dramatically by election day.

However, his forecast indicates a strong momentum favoring Democrats. The Democrats' odds of winning the majority have increased from 71.5% on October 14 to 77.6% as of October 23. While Miller's forecast may not be the most accurate, it offers a compelling perspective suggesting that the race may not be as close as polls indicate, and that the Trump effect may be detrimental to the GOP.