2010 Senate · MA
Mellman Group · fieldwork ended 2010-01-09 (10 days before the election) · 800 respondents · Live Phone · partisan sponsor (DEM)
The poll said
Democrat 50% · Republican 36%
D+14.0
The certified result
Democrat 47.09% · Republican 51.86%
R+4.8
The arithmetic
- Poll margin = 50 − 36 = 14.00
- Actual margin = 47.095 − 51.860 = -4.765
- Signed miss = 14.00 − (-4.765) = 18.764
- Absolute miss = |18.764| = 18.764
The poll overstated the Democrat by 18.8 points and had the wrong leader.
Where these numbers come from
Poll and result: 538 raw_polls.csv. Poll ID 63699, race ID 1526 (538 database).