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1998 Senate · IL

Mason-Dixon Polling & Strategy · fieldwork ended 1998-10-25 (9 days before the election) · 813 respondents · Live Phone

The poll said

Democrat 41% · Republican 49%

R+8.0

The certified result

Democrat 47.44% · Republican 50.35%

R+2.9

The arithmetic

  1. Poll margin = 41 − 49 = -8.00
  2. Actual margin = 47.444 − 50.347 = -2.903
  3. Signed miss = -8.00 − (-2.903) = -5.097
  4. Absolute miss = |-5.097| = 5.097

The poll overstated the Republican by 5.1 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 26126, race ID 1728 (538 database).