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2018 House · CA-48

Monmouth University Polling Institute · fieldwork ended 2018-10-19 (18 days before the election) · 372 respondents · Live Phone

The poll said

Democrat 46% · Republican 52%

R+6.0

The certified result

Democrat 53.55% · Republican 46.45%

D+7.1

The arithmetic

  1. Poll margin = 46 − 52 = -6.00
  2. Actual margin = 53.552 − 46.448 = 7.104
  3. Signed miss = -6.00 − (7.104) = -13.104
  4. Absolute miss = |-13.104| = 13.104

The poll overstated the Republican by 13.1 points and had the wrong leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 56374, race ID 235 (538 database).