Don't trust the polls? You should. They've been fairly accurate so far this election cycle.

It might be hip to say that the ...

Posted: May 3, 2018 5:11 AM
Updated: May 3, 2018 5:11 AM

It might be hip to say that the "polls are broken" or the "polls are wrong," but so far this cycle, it has not been true.

There have been nine congressional (House and Senate) and governor elections with polling in 2017 and 2018, and the polling from them has been pretty good, historically speaking. Let's take a look first at the six special House elections with polling in the final three weeks of the campaigns: Arizona 8, Georgia 6 (the special election and runoff), Montana at large, Pennsylvania 18 and South Carolina 5.

Among the 27 polls across these six contests, the average absolute error per poll was just 4.0 points. That's actually 1.1 points better than the average poll in House specials from 2004 to 2016, which was 5.1 points. The average public poll in the recent Arizona 8 special election, for example, was off by only 4.1 points from the final result. All the polls suggested a far tighter race than the +25 Republican partisan lean of the district.

The same story can be told when looking at the three major statewide contests this cycle: Alabama US Senate, New Jersey governor and Virginia governor. Of the 31 polls conducted in the two governor contests, the average error was 5.2 percentage points or right about at the 5.1 percentage point average for polling dating from 1998 to 2015. The average error in New Jersey was just 1.7 points, compared with 6.6 points in the highly polled Virginia race.

The average error for the 16 polls in the final three weeks of the Alabama Senate race was 5.9 percentage points. That may seem high but it's really not for a special election held in December of an off year. The average error for Senate elections not held on Election Day of a midterm of a presidential year from 1998 to 2016 was 5.8 percentage points. Among the three gold standard pollsters (i.e. those who use live interviews, call cellphones and are transparent about their methodology), the average error dropped to only 3.8 percentage points.

All the polls in Alabama signaled that the race could be tight. As I've said before, polls are tools. In Alabama, these tools told us that the race was going to be far tighter than we'd expect for a Senate race in a state Trump won by nearly 30 points.

Of course, many of the complaints about polling after 2016 had little to do with the accuracy of individual polls. They had to do with the fact that polling overall seemed to be biased against Republicans. I always thought these critiques were lousy because arguments were made in the reverse direction after 2012. The bias against a particular party in the polls, however, changes from year to year and is more random than anything else.

That's why it's not surprising that the polls have not been biased against the Republicans in the off-year cycle. Across the eight races this cycle with polls in which there was only one Democrat and only one Republican, the Democrats have done on average 1.5 percentage points better than the average poll in the final three weeks of the campaigns.

The errors have been mostly random. Republicans did better in the Georgia 6 runoff and Pennsylvania 18 special. Democrats did better in the Alabama Senate and Virginia governor's races. The randomness of the errors is exactly what you'd expect given history.

Turning to the fall campaign this year, the randomness of the poll errors so far is a sign that neither side should be expecting to do better than the polls. Democrats cannot count on outperforming their polls even if the generic congressional ballot is not showing the same shift toward the Democrats as the special elections have. Republicans cannot count on the polls being off, even though Republicans and Trump did better than the polls in 2016.

None of this is to say the polls will be perfect. Rather, we just don't know who is going to do better than the polls suggest.

Minnesota Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 98447

Reported Deaths: 2072
CountyConfirmedDeaths
Hennepin27557932
Ramsey11167323
Dakota7692126
Anoka6281137
Stearns409424
Washington391855
Scott264833
Olmsted253528
Nobles197916
Blue Earth17366
St. Louis172542
Wright17017
Carver14467
Clay142441
Rice13478
Mower13446
Sherburne117714
Kandiyohi10563
Winona92018
Lyon7334
Waseca7228
Benton5633
Steele5552
Crow Wing55418
Nicollet54717
Freeborn5464
Watonwan5354
Chisago5171
Todd5072
McLeod5022
Le Sueur4764
Otter Tail4694
Beltrami4605
Martin44611
Goodhue3899
Pine3550
Douglas3522
Itasca35215
Polk3274
Isanti3191
Becker2842
Carlton2791
Morrison2702
Dodge2610
Pipestone23810
Chippewa2321
Cottonwood2290
Meeker2132
Wabasha2060
Sibley2023
Yellow Medicine1982
Brown1962
Cass1864
Rock1810
Redwood1783
Murray1742
Mille Lacs1693
Renville1618
Jackson1531
Unassigned15352
Faribault1470
Swift1441
Fillmore1330
Houston1300
Kanabec1288
Roseau1260
Koochiching1233
Hubbard1221
Pennington1201
Lincoln1180
Stevens1071
Pope1000
Aitkin841
Big Stone830
Wadena730
Wilkin713
Lac qui Parle681
Grant634
Lake600
Norman560
Marshall531
Mahnomen491
Red Lake451
Traverse340
Clearwater310
Lake of the Woods241
Kittson120
Cook70

Iowa Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 87828

Reported Deaths: 1332
CountyConfirmedDeaths
Polk16113264
Woodbury559768
Johnson517927
Black Hawk454192
Linn4163114
Story348517
Dubuque340242
Scott309528
Dallas282938
Pottawattamie220139
Buena Vista200312
Marshall179434
Sioux17073
Wapello134157
Webster131714
Plymouth118221
Clinton113921
Muscatine112855
Crawford11086
Cerro Gordo106421
Warren9696
Jasper87034
Des Moines8068
Henry7734
Marion7728
Tama75332
Carroll6955
Lee6527
Wright5971
Dickinson5426
Boone5268
Bremer5067
Washington48511
Delaware4413
Louisa43415
Mahaska42720
Lyon3754
Jackson3583
Floyd3573
Franklin35218
Clay3434
Winneshiek3408
Benton3381
Hamilton3343
Winnebago32313
Hardin3111
Poweshiek3118
Buchanan2921
Jones2893
Kossuth2860
Butler2792
Emmet27510
Chickasaw2701
Shelby2701
Clarke2693
Clayton2683
Sac2670
Allamakee2656
Guthrie2649
Harrison2593
Cherokee2572
Cedar2531
Fayette2382
Madison2342
Grundy2294
Iowa2221
Palo Alto2080
Hancock1992
Mitchell1970
Humboldt1943
Howard1927
Mills1911
Page1910
Calhoun1883
Osceola1770
Cass1762
Pocahontas1662
Monona1621
Monroe16211
Lucas1566
Appanoose1443
Union1423
Jefferson1401
Taylor1341
Davis1284
Ida1281
Fremont1220
Keokuk1191
Van Buren1181
Worth1090
Greene1050
Montgomery995
Audubon891
Wayne882
Adair731
Decatur670
Ringgold532
Adams330
Unassigned140
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