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2004 Senate · PA

Mason-Dixon Polling & Strategy · fieldwork ended 2004-10-20 (13 days before the election) · 800 respondents · Live Phone

The poll said

Democrat 32% · Republican 50%

R+18.0

The certified result

Democrat 41.99% · Republican 52.62%

R+10.6

The arithmetic

  1. Poll margin = 32 − 50 = -18.00
  2. Actual margin = 41.987 − 52.618 = -10.631
  3. Signed miss = -18.00 − (-10.631) = -7.370
  4. Absolute miss = |-7.370| = 7.370

The poll overstated the Republican by 7.4 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 25191, race ID 1641 (538 database).