2012 House · IL-8
Market Shares Corp. · fieldwork ended 2012-10-22 (15 days before the election) · 600 respondents · Live Phone
The poll said
Democrat 50% · Republican 40%
D+10.0
The certified result
Democrat 54.74% · Republican 45.26%
D+9.5
The arithmetic
- Poll margin = 50 − 40 = 10.00
- Actual margin = 54.742 − 45.258 = 9.484
- Signed miss = 10.00 − (9.484) = 0.516
- Absolute miss = |0.516| = 0.516
The poll overstated the Democrat by 0.5 points and had the right leader.
Where these numbers come from
Poll and result: 538 raw_polls.csv. Poll ID 51354, race ID 5035 (538 database).