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2010 Senate · PA

Public Policy Polling · fieldwork ended 2010-10-17 (16 days before the election) · 718 respondents · IVR

The poll said

Democrat 46% · Republican 45%

D+1.0

The certified result

Democrat 48.99% · Republican 51.01%

R+2.0

The arithmetic

  1. Poll margin = 46 − 45 = 1.00
  2. Actual margin = 48.992 − 51.008 = -2.016
  3. Signed miss = 1.00 − (-2.016) = 3.017
  4. Absolute miss = |3.017| = 3.017

The poll overstated the Democrat by 3.0 points and had the wrong leader.

Where these numbers come from

Poll and result: 538 raw_polls.csv. Poll ID 32585, race ID 1537 (538 database).