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2010 Senate · MA

American Research Group · fieldwork ended 2010-01-13 (6 days before the election) · 600 respondents · Live Phone

The poll said

Democrat 45% · Republican 48%

R+3.0

The certified result

Democrat 47.09% · Republican 51.86%

R+4.8

The arithmetic

  1. Poll margin = 45 − 48 = -3.00
  2. Actual margin = 47.095 − 51.860 = -4.765
  3. Signed miss = -3.00 − (-4.765) = 1.764
  4. Absolute miss = |1.764| = 1.764

The poll overstated the Democrat by 1.8 points and had the right leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 63617, race ID 1526 (538 database).