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2002 Senate · IL

SurveyUSA · fieldwork ended 2002-10-29 (7 days before the election) · 528 respondents · IVR

The poll said

Democrat 56% · Republican 37%

D+19.0

The certified result

Democrat 60.33% · Republican 38.02%

D+22.3

The arithmetic

  1. Poll margin = 56 − 37 = 19.00
  2. Actual margin = 60.334 − 38.020 = 22.314
  3. Signed miss = 19.00 − (22.314) = -3.314
  4. Absolute miss = |-3.314| = 3.314

The poll overstated the Republican by 3.3 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 54700, race ID 1655 (538 database).