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2018 Senate · MT

Harris Insights & Analytics · fieldwork ended 2018-10-28 (9 days before the election) · 700 respondents · Online Panel

The poll said

Democrat 48% · Republican 41%

D+7.0

The certified result

Democrat 50.33% · Republican 46.78%

D+3.6

The arithmetic

  1. Poll margin = 48 − 41 = 7.00
  2. Actual margin = 50.334 − 46.782 = 3.552
  3. Signed miss = 7.00 − (3.552) = 3.449
  4. Absolute miss = |3.449| = 3.449

The poll overstated the Democrat by 3.4 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 73033, race ID 110 (538 database).