Siena College
Graded against the actual result across 75 races (from 141 polls, through 2024).
Head-to-head vs the VotePredictor model
The fair, apples-to-apples test: on the 74 races Siena College actually polled, how its final poll's margin compared to what the VotePredictor model predicted for those same races.
| Model | Avg miss (pts) | Called right |
|---|---|---|
| Siena College | 5.46 | 88% |
| VotePredictor | 5.68 | 84% |
VotePredictor aggregates all the pollsters, so it's expected to beat any single one on margin — that's the value of averaging. The honest comparison among forecasters is on the combined board.
Every race (75)
Each race Siena College polled, scored on its final poll — the call right before the vote — against the actual Dem−Rep result. Click a race for its full detail.
Accuracy by time to election
Lower is better. Time to election runs right (election week) to left (~2 months out).
By the numbers
| Time to election | Polls | Avg miss | vs field | Called right |
|---|---|---|---|---|
| ≤1 wk | 15 | 6.45 | +2.17 | 87% |
| 1–3 wk | 40 | 5.19 | +0.12 | 93% |
| 3–6 wk | 51 | 7.79 | +2.05 | 69% |
| 6–9 wk | 35 | 8.05 | +1.90 | 80% |
vs field is this pollster's average miss minus all pollsters' at the same lead time — green beats the field, redtrails it. Our historical polls reach ~2 months out; earlier polling isn't in the record.
Track record by cycle — getting better?
| Year | Polls | Avg miss | Lean (house effect) |
|---|---|---|---|
| 2006 | 8 | 9.9 | D+0.9 |
| 2008 | 3 | 10.9 | R+9.5 |
| 2009 | 7 | 19.2 | R+18.3 |
| 2010 | 21 | 5.5 | R+1.0 |
| 2011 | 4 | 8.6 | R+4.7 |
| 2012 | 21 | 7.6 | R+7.0 |
| 2014 | 16 | 5.9 | D+2.9 |
| 2016 | 16 | 4.0 | R+2.7 |
| 2018 | 9 | 6.9 | R+6.9 |
| 2020 | 4 | 6.8 | D+6.8 |
| 2022 | 23 | 5.7 | D+4.4 |
| 2024 | 5 | 6.9 | D+5.3 |
Do we credit a pollster for fixing its bias? Each cycle, the model re-estimates every pollster's lean from all its earlier polls (walk-forward) and subtracts it before using the poll. We tested weighting recent cycles more — it doesn't help: a pollster's lean in one cycle barely predicts the next (correlation 0.28), so the swings above are mostly noise, and averaging over more history beats chasing the latest cycle. The all-time estimate we use came out within ~0.5% of the best option.