Our model operates uniquely, focusing solely on the most recent poll conducted in each state or district. Unlike methods relying on polling averages, which encompass data collected over prolonged periods, we prioritize the latest polling data. We recognize that the national mood fluctuates daily, shaped by various factors such as stock market performance, prevailing global and local events, and even weather conditions influencing human behavior. By analyzing the freshest polling data from every state, our aim is to accurately capture the latest voting trends.

Market-based Odds
Our market-based odds are derived from prediction and betting markets, which we have been tracking since the 2016 election. For 2024, we calculate the probability for each race using bid/ask data from the relevant futures contracts at Polymarket, a leading prediction market platform. Market-based odds respond quickly to late-breaking news and can be a lead indicator pending updated polling results.

Poll-based Odds vs Market-based Odds - Which is better?
Both are valuable!
Ideally, poll-based and market-based odds would closely align for each race, and thus have similar overall forecasts. By utilizing the latest poll, we access the most current data; however, polls only capture a snapshot in time, and their release date can be several days after the actual survey period. In contrast, market-based odds are continuously updated through 24-hour trading, providing real-time insights for every race, especially in response to late-breaking news or emerging trends. However, as election day nears, the frequency of polls will increase substantially, and our track record for poll-based projections of the presidential election has been perfect.

Qualifying Polls
To qualify for inclusion, a poll must meet these criteria:

• The Poll must be listed at fivethirtyeight.com
• The Poll must report the survey date(s), methodology, sample size, and the % of votes for each candidate.
• The Poll must NOT be an internal poll, funded by a candidate or their PAC, or require a subscription to obtain relevant data.
• The methodology must include a Live or IVR (Interactive Voice Response) component; polls that are exclusively online are excluded.
• The Polling date, or the midpoint of a multi-day poll, must be the most recent for that race. If multiple polls share the same date, the poll with the larger sample size is selected.
• The Poll must sample "Registered Voters" or "Likely Voters." We use the results with "Leaners," when available.
• For Presidential polls, we use results with the most candidate choices. For example, if a poll reports 3-candidate race results and 4-candidate race results, we use the 4-way results.