the data diary

The final pre-election forecast gives Donald Trump a 70% chance of beating Kamala Harris in Arizona.

Presidential probabilities

Each day, the model simulates thousands of plausible election results, from landslide victories to tightly contested races. Each candidate’s probability of winning is the proportion of simulations that they’ve won.

Forecasted election-day voteshare

The model first constructs a polling average, pooling data across similar states when polls are sparse. It then projects forward to election day, initially relying on non-polling indicators like economic growth and partisanship, but aligning more closely with the polling average as election day approaches.

pollster

date

population

mode

sample size

harris

trump

margin

AtlasIntel

4 November

Likely voters

Online Ad

859

47.4%

52.6%

R +5.2%

Patriot Polling

3 November

Registered voters

IVR/Text-to-Web

790

48.2%

51.8%

R +3.5%

Victory Insights

3 November

Likely voters

IVR/Text-to-Web

732

49.6%

50.4%

R +0.8%

AtlasIntel

2 November

Likely voters

Online Ad

949

46.7%

53.3%

R +6.6%

The New York Times/Siena College

2 November

Likely voters

Live Phone

963

47.9%

52.1%

R +4.3%

InsiderAdvantage

2 November

Likely voters

Unknown

763

48.5%

51.5%

R +3.0%

Emerson College

2 November

Likely voters

IVR/Online Panel/Text-to-Web

895

48.9%

51.1%

R +2.1%

Focaldata

1 November

Likely voters

Online Panel

1,726

49.5%

50.5%

R +1.0%

AtlasIntel

31 October

Likely voters

Online Ad

983

47.8%

52.2%

R +4.4%

SoCal Research

31 October

Likely voters

Online Panel

736

49.6%

50.4%

R +0.8%

1–10 of 94 rows

...

State similarities

The model uses state characteristics, like demographic composition, population density, and education, to estimate how similar states are to one another. Similar states are more likely to share polling biases and see similar shifts in polling trendlines.

Sources: Ballotpedia; Cook Political Report; The Economist; Federal Reserve Bank of St. Louis; FiveThirtyEight; Urban Stats; 270towin.com

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