Oh, and another thing, this map just shows which states are trending more GOP/Dem compared to each other. If the GOP or the Dems win the nation 60-40 then they will win the states trending against them.
First, a simple four year comparison on a vote for one office is in and of itself an insufficent basis for asserting a 'trend.'
Second, lets look at some of the specific states in which you formula produces a signficant 'trend.':
Connecticut - a Republican trend, or is it just the case Joe Lieberman
was the VP nominee in 2000, which increased the D vote
in that state in 2000?
Tennessee - a Republican trend, or is it just that Al Gore was the
Presidential nominee in 2000, which increase the D vote
in that state in 2000?
N. Carolina - Is it possible that Edwards helped add votes in that state?
N. Jersey - McGreevy!
S. Dakota - Daschle turned out the D's this year in a forlorn attempt to
save his seat.
Hawaii - As has previously been noted, Hawaii has a history of
giving Republican incumbent Presidents seeking reelection
a better percentage of the vote than would otherwise be
the case.
Alabama - Kerry abandoned Alabama (i.e. no real campaign there)
Vermont - Bush abandoned Vermont (i.e. no real campaign there)
R. Island - Same as Hawaii.
