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2018 House · PA-18

Monmouth University Polling Institute · fieldwork ended 2018-03-10 (3 days before the election) · 372 respondents · Live Phone

The poll said

Democrat 49% · Republican 47%

D+2.0

The certified result

Democrat 49.86% · Republican 49.53%

D+0.3

The arithmetic

  1. Poll margin = 49 − 47 = 2.00
  2. Actual margin = 49.863 − 49.533 = 0.330
  3. Signed miss = 2.00 − (0.330) = 1.670
  4. Absolute miss = |1.670| = 1.670

The poll overstated the Democrat by 1.7 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 51023, race ID 1759 (538 database).