Impact Research
Graded against the actual result across 74 races (from 93 polls, through 2024).
Head-to-head vs VotePredictor Elections
The fair, apples-to-apples test: on the 74 races Impact Research actually polled, how its final poll's margin compared to what VotePredictor Elections predicted for those same races.
| Model | Avg miss (pts) | Called right |
|---|---|---|
| Impact Research | 6.51 | 65% |
| VotePredictor Elections | 4.66 | 80% |
VotePredictor Elections 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 (74)
Each race Impact Research 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 |
|---|---|---|---|---|
| 1–3 wk | 12 | 5.33 | +0.27 | 58% |
| 3–6 wk | 49 | 6.34 | +0.64 | 74% |
| 6–9 wk | 31 | 7.31 | +1.17 | 58% |
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) |
|---|---|---|---|
| 2004 | 4 | 7.6 | D+7.6 |
| 2006 | 4 | 3.7 | R+1.6 |
| 2008 | 15 | 6.0 | D+1.6 |
| 2010 | 12 | 8.9 | D+8.9 |
| 2012 | 13 | 5.8 | D+4.9 |
| 2014 | 3 | 7.9 | D+7.9 |
| 2016 | 8 | 10.1 | D+10.1 |
| 2018 | 12 | 3.2 | D+2.1 |
| 2020 | 11 | 7.9 | D+7.9 |
| 2022 | 5 | 4.8 | D+2.8 |
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.