2010 Senate · IL
Impact Research · fieldwork ended 2010-10-27 (6 days before the election) · 400 respondents · Live Phone · partisan sponsor (DEM)
The poll said
Democrat 39% · Republican 37%
D+2.0
The certified result
Democrat 46.42% · Republican 48.02%
R+1.6
The arithmetic
- Poll margin = 39 − 37 = 2.00
- Actual margin = 46.416 − 48.015 = -1.599
- Signed miss = 2.00 − (-1.599) = 3.599
- Absolute miss = |3.599| = 3.599
The poll overstated the Democrat by 3.6 points and had the wrong leader.
Where these numbers come from
Poll and result: 538 raw_polls.csv. Poll ID 32809, race ID 1518 (538 database).