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2020 Senate · IA

InsiderAdvantage · fieldwork ended 2020-10-30 (4 days before the election) · 400 respondents · IVR/Live Phone

The poll said

Democrat 45.1% · Republican 50.7%

R+5.6

The certified result

Democrat 45.15% · Republican 51.74%

R+6.6

The arithmetic

  1. Poll margin = 45.1 − 50.7 = -5.60
  2. Actual margin = 45.152 − 51.740 = -6.588
  3. Signed miss = -5.60 − (-6.588) = 0.988
  4. Absolute miss = |0.988| = 0.988

The poll overstated the Democrat by 1.0 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 72492, race ID 6272 (538 database).