Head-to-head vs VotePredictor Elections
The fair, apples-to-apples test: on the 41 races GBAO actually polled, how its final poll's margin compared to what VotePredictor Elections predicted for those same races.
| Model | Avg miss (pts) | Called right |
|---|---|---|
| GBAO | 5.71 | 71% |
| VotePredictor Elections | 3.85 | 78% |
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 (41)
Each race GBAO 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 | 5.43 | +0.37 | 67% |
| 3–6 wk | 22 | 5.91 | +0.21 | 64% |
| 6–9 wk | 17 | 6.23 | +0.09 | 71% |
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) |
|---|---|---|---|
| 2012 | 8 | 3.8 | R+0.6 |
| 2014 | 3 | 7.7 | D+7.7 |
| 2016 | 9 | 6.0 | D+5.6 |
| 2018 | 9 | 2.9 | R+0.3 |
| 2020 | 17 | 7.7 | D+7.7 |
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.