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2004 Senate · IA

Opinion Dynamics · fieldwork ended 2004-10-30 (3 days before the election) · 700 respondents · Live Phone

The poll said

Democrat 20% · Republican 67%

R+47.0

The certified result

Democrat 27.88% · Republican 70.18%

R+42.3

The arithmetic

  1. Poll margin = 20 − 67 = -47.00
  2. Actual margin = 27.877 − 70.184 = -42.307
  3. Signed miss = -47.00 − (-42.307) = -4.693
  4. Absolute miss = |-4.693| = 4.693

The poll overstated the Republican by 4.7 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 25110, race ID 1627 (538 database).