Fun With Numbers: Predicting Pennsylvania turnout Based on Current Data

I made a little spreadsheet to predict Pennsylvania results. It's based on the following inputs and assumptions:

  • Turnout in 2020 was 6,835,000. Turnout in 2016 was 5,896,000. Turnout this year is assumed to be 95% of 2020 turnout, so 6,493,000.

  • The early vote is currently D/R/I 285k/95k/25k. Smithley expects about 1.9 million early ballot requests. Assuming an 85% return rate overall and extrapolating current trends that makes the early vote D/R/I 1109k/370k/136k with 1,615,000 early ballots cast overall.

  • Partisans are expected to split 95/5 regardless of vote mode. Independents, again per Smithley, are expected to split 70/30 when voting by mail, but I've also calculated their overall expected vote, which can vary but for now let's assume they split 50/50. (What actually matters is the overall split, FWIW.)

  • Election day is the remaining 4,878,000 voters. Republicans won ED turnout by 11-12% in '22 and '23, but Smithley expects more like R+15% this year. Independents are assumed to be 15% of the ED vote, which means the the remaining turnout is 50% Republican and 35% Democrat. (Indies vote Trump 53%/Harris 47% to maintain an overall 50-50 tie among the group).

  • Republicans win the election day vote 2790k Trump - 2088k Harris.

  • Harris wins overall by 0.3%, or about 18k votes.

  • This result is extremely sensitive to how Indies lean. If indies break 51-49 for Trump, Trump wins. Harris is already ahead so if she wins Indies (which in most polls I've seen she does) then it's an increasingly comfortable win for Harris.

  • Turnout, as a percentage of active voter registrations in PA, would be 79.4% for Dems, 82.8% for Republicans, and 70.1% for independents.

  • If Democrats turn out at a slightly higher rate, even just matching Rs (they are returning their ballots more quickly right now, after all) then basically every point of turnout edge Dems gain is a point on margin for Harris.

  • I feel like 95% of 2020 turnout is pretty realistic, but since the EV is locked in by Smithley's estimate and the remainder is ED vote, higher turnout helps Trump and lower turnout helps Harris (basically, the higher the proportion of the total vote the EV is, the better we should assume Harris does). If turnout is the same as 2016 Harris wins by about 2%. If turnout is the same as 2020 Trump wins by 0.4%.