Poll Average Details- PA US Senate - D Primary - 2010-05-18 19:00:00

The Poll Average is a weighted and adjusted number.
[Mid Date Column] All times are calculated by the middle date of the poll if it spans multiple days.
A time window of 2 months prior to the most recent poll is used.
[Time Weight Column] Polls are weighted in the amount they contribute to the final results in a linear fashion in this time window - the newest poll has a weight of 1, a poll 30 days prior will have a weight of 0.5 and a poll 60 days out will have a weight of 0. If the same pollster has more than one poll in this time period, only the newest will be used.
[Internal Column] If a poll is marked as being an internal poll for one of the candidates, it's weight will be halved.
[Candidate Columns, Bias] OurCampaigns has calculated partisan bias figures for all Polling Firms based on data from final vote totals in races they have polled. These amounts are subtracted from the poll result - in the case the bias figure is negative it will effectively be added to the poll result and appear as two dashes (minus a negative = plus). [TOTAL Row] The adjusted weights are summed for each poll result and the adjusted poll results for each candidate are multiplied by the poll weight and then summed. Each candidate's poll sum is divided by their weight sum to give the total.

Poll	Mid Date	Time Weight	Internal	Joseph A. Sestak Joseph A. Sestak	Arlen Specter Joseph A. Sestak
Quinnipiac University	5/16	X 1.00000		42.0000	41.0000
Muhlenberg College	5/15	X 0.98333		44.0000	44.0000
Suffolk University	5/13	X 0.95000		49.0000	40.0000
Research 2000	5/12	X 0.93333		45.0000	43.0000
Franklin & Marshall College	5/9	X 0.88333		38.0000	36.0000
Rasmussen Reports	5/6	X 0.83333		47.0000	42.0000
Unknown (D)	4/28	X 0.70000		38.0000	47.0000
Susquehanna Polling & Research (SP&R)	4/12	X 0.43333		28.0000	42.0000
TOTAL				42.473945	41.732010