LUNCHTIME POLITICS: What Happened in 2020 Senate Polling

Your Daily Polling Update for Tuesday, December 29, 2020

WHAT HAPPENED?

A hard look at state polls in the 2020 Senate Elections
Part 3 in a series

Overall:
To get a handle on how the polls did in the 2020 Senate elections, we selected a dozen key races and looked at the final polls in each race. Here are our findings: 

  • Individual polls: Of the total 90 individual polls we used for this study, 57 indicated the right winner, 32 indicated the wrong winner and one showed a tie. Put another way: 63% of the final polls in key Senate races indicated the right winners
  • Polling averages: Final polling averages in these 12 elections indicated the right winner in eight races, the wrong winner in three races and didn’t indicate a winner in one race. Put another way: 67% of the final polling averages in key Senate races indicated the right winners.

States with the worst Senate polling:

  • Maine (all four polls indicated the wrong winner; the average poll margin was off by 12.4 points from the actual result) 
  • Montana (three of four polls indicated the wrong winner; the average poll margin was off 9.5 points from the actual result).
  • Iowa (four of six polls indicated the wrong winner; the average poll margin was off 6.6 points from the actual result)
  • North Carolina (13 of 14 polls indicated the wrong winner and the average poll margin was off 5 points from the actual result)
  • Note that in each of the four states above, Republican incumbents did better in the election than most polls in their states had indicated.

Final polls included that missed actual election margins by the most points:

  • SOUTH CAROLINA SENATE: Swayable had the wrong winner and was off the final election result by 16.3 points
  • MAINE SENATE: Emerson College had the wrong winner and was off the final election result by 14.6 points
  • MICHIGAN SENATE: Research Co. had the right winner but was off the final election result by 13.3 points
  • NORTH CAROLINA SENATE: NBC/Marist had the wrong winner and was off the final election result by 11.8 points
  • MONTANA SENATE: PPP and MSU-Billings each had the wrong winner and was off the final election result by 11 points
  • IOWA SENATE: Emerson College and Data for Progress each had the wrong winner and was off the final election result by 10.6 points

State with the best Senate polling:

  • Colorado (All polls indicated the right winner and the polling average came within seven-tenths of a point of the actual election result).

STATES WHERE POLLING AVERAGES INDICATED RIGHT WINNERS:
 
COLORADO

  • Poll average indicated the right winner; the average poll margin was only seven-tenths of a point off the actual election result  
  • John Hickenlooper (D) defeated Sen. Cory Gardner (R) by 9.3 points
  • Final poll average: Hickenlooper +10
  • All five polls indicated the right winner
  • Poll indicating the right winner closest to actual margin: Data for Progress (Hickenlooper +9)
  • Poll indicating the right winner by most overstated margin: Swayable (Hickenlooper +14, off by 4.7 points)

ARIZONA

  • Poll average indicated the right winner; the average poll margin was 2.8 points off from the actual election result  
  • Mark Kelly (D) defeated Sen. Martha McSally (R) by 2.4 points
  • Final poll average: Kelly +5.2
  • All 11 polls indicated the right winner
  • Polls indicating the right winner closest to actual margin: Emerson College (+3) and Grand Canyon (+3)
  • Poll indicating the right winner but by most overstated margin: Swayable (Kelly +10, off by 7.6 points)

MICHIGAN

  • Poll average indicated the right winner; the average poll margin was 6.8 points off the actual election result  
  • Sen. Gary Peters (D) defeated John James (R) by 1.7 points
  • Final poll average: Peters +8.5
  • All 13 polls indicated the right winner
  • Polls indicating the right winner closest to actual margin: EPIC/MPA (Peters +5), CNBC/Change Research (Peters +5), Emerson College (Peters +5) and Mitchell Research (Peters +5)
  • Poll indicating the right winner by most overstated margin: Research Co. (Peters +15, off by 13.3 points)

MINNESOTA

  • Poll average indicated the right winner; the average poll margin was 3.1 points off the actual election result  
  • Sen. Tina Smith (D) defeated Jason Lewis (R) by 5.3 points
  • Final poll average: Smith +8.4
  • All five polls indicated the right winner
  • Polls indicating the right winner closest to actual margin: SurveyUSA (Smith +3)
  • Polls indicating the right winner but by most overstated margin: Research Co. (Smith +11, off by 5.7 points)

TEXAS

  • Poll average indicated the right winner; the average poll margin was off 3.1 points from the actual election result 
  • Sen. John Cornyn (R) defeated MJ Hegar (D) by 9.6 points
  • Final poll average: Cornyn +6.5
  • All eight polls indicated the right winner
  • Poll indicating the right winner closest to actual margin: NYT/Siena (Cornyn +10)
  • Poll indicating the right winner by the most understated margin: Morning Consult (Cornyn +4, off by 5.6 points)

SOUTH CAROLINA

  • Poll average indicated the right winner; the average poll margin was 6.8 points off the actual election result  
  • Sen. Lindsey Graham (R) defeated Jaime Harrison (D) by 10.3 points
  • Final poll average: Graham +3.5
  • Five polls indicated the right winner, one poll indicated the wrong winner
  • Poll indicating the right winner closest to actual margin: Optimus (Graham +10)
  • Poll indicating the wrong winner by most overstated margin: Swayable (Harrison +6, off by 16.3 points)

ALABAMA

  • Poll average indicated the right winner; the average poll margin was 7.6 points off the actual election result margin  
  • Tommy Tuberville (R) defeated Sen. Doug Jones (D) by 20.4 points
  • Final poll average: Tuberville +12.8
  • All four polls indicated the right winner
  • Poll indicating the right winner closest to actual margin: Swayable (Tuberville +16)

MONTANA

  • Poll average indicated the right winner; the average poll margin was 9.5 points off the actual election result  
  • Sen. Steve Daines (R) defeated Steve Bullock (D) by 10 points 
  • Final poll average: Daines +0.5 points
  • One poll indicated the right winner, two polls indicated the wrong winner and one poll had the race even
  • Poll indicating the right winner closest to actual margin: Change Research (Daines +4)
  • Polls indicating the wrong winner by most overstated margin: PPP (Bullock +1, off by 11 points) and MSU-Billings (Bullock +1, off by 11 points)

 
STATES WHERE POLLING AVERAGES INDICATED WRONG WINNERS:
 
GEORGIA (regular election)*

  • Poll average indicated the wrong leader; the average poll margin was 3 points off the actual election result  
  • Sen. David Perdue (R) led Jon Ossoff (D) by +1.8 points
  • Four polls indicated the wrong winner and two indicated the right winner
  • Final poll average: Ossoff +1.2
  • Poll indicating the right winner closest to actual margin: WSB-TV/Landmark (Perdue +2)
  • Poll indicating the wrong winner by most overstated margin: Data for Progress (Ossoff +5, off by 6.8 points)

*Note that we did not include the Georgia special election because the race had multiple Republican and Democratic candidates.
 
NORTH CAROLINA

  • Poll average indicated thewrong winner; the average poll margin was 5 points off the actual election result  
  • Sen. Thom Tillis (R) defeated Cal Cunningham (D) by 1.8 points
  • Final poll average: Cunningham +3.2
  • 13 of 14 polls indicated the wrong winner
  • The one poll indicating the right winner: Cardinal Point (R) Tillis +5
  • Poll indicating the wrong winner by most overstated margin: NBC/Marist (Cunningham +10, off by 11.8 points)

MAINE

  • Poll average indicated thewrong winner; the average poll margin was 12.4 points off the actual election result  
  • Sen. Susan Collins (R) defeated Sara Gideon (D) by 8.6 points
  • Final poll average: Gideon +3.8
  • All four polls indicated the wrong winner
  • Poll indicating the wrong winner by most overstated margin: Emerson College (Gideon +6, off by 14.6 points)


STATE WHERE POLLING AVERAGE INDICATED A TIE:
 
IOWA

  • Poll average indicated the race even; the average poll margin was 6.6 points off the actual election result  
  • Sen. Joni Ernst (R) defeated Theresa Greenfield (D) by 6.6 points
  • Final poll average: Even
  • Two polls indicated the right winner, four polls indicated wrong winner
  • Poll indicating the right winner closest to actual margin: Insider Advantage (Ernst +6)
  • Polls indicating the wrong winner by most overstated margin: Emerson College (Greenfield +4, off by 10.6 points), Data for Progress (Greenfield +4, off by 10.6 points) 

________________

NOTE ON THIS POST-ELECTION SERIES
: The purpose of this series is neither to indict nor to vindicate the polling industry. We simply want to present the facts and explain, to the best of our ability with the data we have, what may have happened and why.

  • The first part of this series (published Nov. 10) focused on national polling.
  • The second part of the series (published Nov. 17) focused on state polls in the presidential election.
  • The third part of the series (today) focuses on Senate polls. 

PERSONAL NOTE: Neither I nor my firm, Certus Insights, conducted any of the public polls in this year’s Senate races that are analyzed in this report. 
––Ron Faucheux

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