Poll Average Details- SD US Senate - 2008-11-04 23:00:00

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	Tim Johnson Tim Johnson	Joel D. Dykstra Charles Lyonel Gonyo
YouGov	11/1	X 1.00000		60.0000 - 1.4663 bias	35.0000 - -0.0047 bias
Greenberg Quinlan Rosner Research (D)	9/25	X 0.38333		61.0000 - 2.2050 bias	34.0000 - -1.6040 bias
TOTAL				58.606108	35.170771