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2017 House · MT-1

Gravis Marketing · fieldwork ended 2017-05-22 (3 days before the election) · 818 respondents · IVR/Online Panel

The poll said

Democrat 35% · Republican 49%

R+14.0

The certified result

Democrat 44.37% · Republican 49.95%

R+5.6

The arithmetic

  1. Poll margin = 35 − 49 = -14.00
  2. Actual margin = 44.365 − 49.951 = -5.586
  3. Signed miss = -14.00 − (-5.586) = -8.414
  4. Absolute miss = |-8.414| = 8.414

The poll overstated the Republican by 8.4 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 50604, race ID 1764 (538 database).