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2020 Senate · IA

Data for Progress · fieldwork ended 2020-10-29 (5 days before the election) · 951 respondents · Online Panel/Text-to-Web

The poll said

Democrat 49% · Republican 45%

D+4.0

The certified result

Democrat 45.15% · Republican 51.74%

R+6.6

The arithmetic

  1. Poll margin = 49 − 45 = 4.00
  2. Actual margin = 45.152 − 51.740 = -6.588
  3. Signed miss = 4.00 − (-6.588) = 10.588
  4. Absolute miss = |10.588| = 10.588

The poll overstated the Democrat by 10.6 points and had the wrong leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 72741, race ID 6272 (538 database).