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2017 Senate · AL

Trafalgar Group · fieldwork ended 2017-12-06 (6 days before the election) · 1,419 respondents · IVR/Email · partisan sponsor (REP)

The poll said

Democrat 45.77% · Republican 50.88%

R+5.1

The certified result

Democrat 49.97% · Republican 48.34%

D+1.6

The arithmetic

  1. Poll margin = 45.77 − 50.88 = -5.11
  2. Actual margin = 49.966 − 48.340 = 1.626
  3. Signed miss = -5.11 − (1.626) = -6.736
  4. Absolute miss = |-6.736| = 6.736

The poll overstated the Republican by 6.7 points and had the wrong leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 50673, race ID 95 (538 database).