Posted by Jim Lindgren:
Best State Poll Predictions were from Rasmussen and Survey USA.--
Polipundit has a [1]nice review of which polls did better in
predicting state results. Rasmussen comes in 2d of the 11 polling
agencies that Polipundit reviews. Survey USA comes in first.
Here are some of the results:
#11 - The LA Times Poll. ... .
#10 - Fox News Poll. ...
#9 - Quinnipiac University Poll. ...
#8 - American Research Group. ...
#7 - Strategic Vision. ...
#6 - Zogby. Mr. "John Kerry Will Win" made predictions in 20
states, and in 13 Battleground States. Zogby got 16 calls right,
and 4 wrong, and was off by an average of 6.10 points. Two of his
final polls were the closest major poll, and another one of his
final polls was off by more than 10 points. In the Battleground
States, Zogby got 9 right, and 4 wrong, and was off by an average
of 4.92 points. [I don't know whether this refers to Zogby's next
to last predictions or the final ones released on Tuesday
afternoon.--Jim]
#5 - Mason-Dixon. M-D made predictions in 24 states, and in 13
Battleground States. M-D got 23 calls right, and 1 wrong, and was
off by an average of 5.75 points. None of their calls was the
closest, but none of their polls was invalidated for being more
than 10 points off. In the Battleground States, M-D got 12 right, 1
wrong, and was off by an average of 5.62 points.
#4 - CNN/USA Today/Gallup - CUG made predictions in 15 states, and
in 12 Battleground States. CUG got 11 calls right and 4 wrong, and
was off by an average of 5.33 points. Two of their final polls was
the closest for that state (both in Battleground States), and none
of their polls were invalidated for being more than 10 points off.
In the Battleground States, CUG got 8 right and 4 wrong, and was
off by an average of 5.33 points.
#3 - Research 2000 - R2K made predictions in 13 states, and in 7
Battleground States. R2K got 12 calls right, and 1 wrong, and was
off by an average of 5.15 points. One of their final polls was the
closest for that state ( in a Battleground State), and none of
their polls were invalidated for being more than 10 points off. In
the Battleground States, R2K got 6 right and 1 wrong, and was off
by an average of 4.57 points.
#2 - A close finish, but number two is Rasmussen Reports. RR made
predictions in 33 states, and in 13 Battleground States. RR got all
their calls correct, without a single miss, and they were off by an
average of 5.82 points. What hurt them was their wide variance of
accuracy in support. Three of their final polls were the closest
for their state, but another 3 of their final polls were off by
more than 10 points. In the Battleground States, RR got all 13
right, and they were off by an average of 4.15 points.
#1 - (drum roll, please) Survey USA. SUSA made predictions in 30
states, and in 9 Battleground States. SUSA got 29 right and 1
wrong, and was off by an average of 3.70 points. So, why does SUSA
win with 29/30, and beat RR take second with 33/33? It comes down
to hitting the bullseye. EIGHTEEN of Survey USA's final polls were
the closest for that state, almost twice as many as every other
major poll PUT TOGETHER! Also, none of their polls were invalidated
for being more than 10 points off. In the Battleground States, SUSA
got 8 right and 1 wrong, and was off by an average of 3.44 points.
Three of SUSA's final polls in Battleground States were the closest
for that state, again the best of any poll.
At least nationally, Rasmussen was weighting by an assumption of equal
numbers of Republicans and Democrats (which turned out to be true),
while most advocates of weighting by party ID were urging this
strategy as a way to weight down the polling results for Republicans
supposedly to correct for the higher percentages of Democrats (as
determined by 2000 exit polling). Rasmussen's [2]final national
prediction was 50.2% for Bush and 48.5% for Kerry (which was off by
less than 2% and got Kerry's share almost exactly).
So from this one election alone, the answer to weighting national
polls would seem to be one of the following:
(1) do not weight by party, which allows you to catch a switch in
party ID (as actually happened in 2004);
(2) weight by party according to exit polling in 2004 (equal numbers
of Republicans and Democrats);
(3) to smooth out extreme swings in party ID in particular polls,
weight by average party ID as revealed in polling done that current
polling season;
(4) guess right about the weight to be used (as Rasmussen did this
year nationally, perhaps with a good reason, perhaps not)
References
1. http://polipundit.com/index.php?p=5180
2. http://www.realclearpolitics.com/bush_vs_kerry_hth.html
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