The 2018 Debrief · post-mortem · permanent archive
How did the polling industry do this cycle?
The 2018 industry MAE landed at 4.5pt — graded across 481 historical races with a known outcome — and 373 polls were analyzed across 96 pollsters. Signed bias −0.42pt: polls landed close to the mean — no systematic over-predict on either side.
INDUSTRY MAE
4.5pt
vs midterm avg
SIGNED BIAS
−0.42pt
D-leaning
POLLS · POLLSTERS
373
96 firms
RACES SCORED
481
w/ known outcome
Industry mean absolute error · 2002–2018
Per-pollster scorecard · 2018 · sorted by MAE
Signed bias · ±4.6pt
MAE · 0–5.5pt
Biggest-miss races · 2018
| Race | Expected | Actual | Miss | Direction |
|---|---|---|---|---|
| us-senate-2018-nm | D+14.00 | D+23.56 | 9.6pt | D-margin underestimate |
| us-governor-2018-ca | D+15.00 | D+23.90 | 8.9pt | D-margin underestimate |
| us-governor-2018-tn | R+12.50 | R+21.01 | -8.5pt | R-margin underestimate |
| us-senate-2018-ny | D+25.00 | D+33.44 | 8.4pt | D-margin underestimate |
| us-governor-2018-ok | R+4.00 | R+12.10 | -8.1pt | R-margin underestimate |
| us-governor-2018-ny | D+17.00 | D+24.53 | 7.5pt | D-margin underestimate |
| us-governor-2018-oh | D+3.00 | R+3.73 | -6.7pt | D-overestimate |
| us-senate-2018-me | R+25.50 | R+19.08 | 6.4pt | R-margin overestimate |