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2014 Senate · IA

Gravis Marketing · fieldwork ended 2014-10-21 (14 days before the election) · 964 respondents · IVR

The poll said

Democrat 43% · Republican 49%

R+6.0

The certified result

Democrat 43.76% · Republican 52.10%

R+8.3

The arithmetic

  1. Poll margin = 43 − 49 = -6.00
  2. Actual margin = 43.761 − 52.100 = -8.339
  3. Signed miss = -6.00 − (-8.339) = 2.339
  4. Absolute miss = |2.339| = 2.339

The poll overstated the Democrat by 2.3 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 34488, race ID 26 (538 database).