Zogby Analytics
740 polls · 236 races · 1998–2020
Average error
5.81
0.26 worse than the 5.55 average.
House effect
R+0.91
Systematically overstates Republicans by this much.
Accuracy rank
#46
of 59 pollsters with 60+ polls.
Methods used: Online Panel, Live Phone, NA
Accuracy by state
Only states where this pollster has at least five matched polls. A house effect that flips sign between states is usually noise; one that holds across many is worth paying attention to.
| State | Polls | Error | House effect |
|---|---|---|---|
| US | 78 | 3.22 | D+0.07 |
| Florida | 50 | 4.26 | D+1.06 |
| Ohio | 46 | 5.28 | R+3.44 |
| Missouri | 41 | 3.51 | D+0.12 |
| New York | 37 | 9.81 | R+9.71 |
| Pennsylvania | 33 | 6.34 | R+5.31 |
| Virginia | 24 | 4.33 | R+1.59 |
| Wisconsin | 24 | 8.21 | R+0.52 |
| Michigan | 23 | 5.19 | R+0.87 |
| Iowa | 23 | 4.56 | D+0.84 |
| Nevada | 21 | 5.30 | R+3.38 |
| Tennessee | 20 | 5.95 | D+3.03 |
| Colorado | 19 | 8.05 | R+0.88 |
| Texas | 19 | 5.39 | D+1.01 |
How this is measured
Every poll is compared to the actual result of the race it was polling. Error is the average absolute miss in points. The house effect is the average signed miss, positive when the poll overstated Democrats — computed only over clean Democrat-versus-Republican matchups, since the sign is meaningless otherwise. 1998–2023 comes from FiveThirtyEight's raw_polls.csv, used under CC BY 4.0 and not endorsed by them; 2024 is our own reconstruction, matching Wayback-recovered 538 poll files to results we compute from MEDSL's county presidential returns and statewide Senate file. Full caveats are on the accuracy overview.