President leads in three states that would cement an Electoral College victory
The Electoral Vote application at the New York Times has allocated all but nine of the states to either Barack Obama or Mitt Romney. In the chart below I have tabulated the number of likely-voter polls conducted in each of those nine states between June 1st, when Romney lined up enough delegates to win the nomination, and October 19th. Rather than examine the size of the difference between the candidates, I took a simpler approach and just counted up the number of polls in which the President held a lead over Mr. Romney. I then used a statistical test called “chi-squared” to see whether the President led in “too many” polls for it to just be the result of chance.
So, to take the case of Nevada, there have been 20 likely-voter polls conducted between June 1st and October 19th, and President Obama has led in 18 of them. If the race were really tied, each candidate should have led in ten of those twenty polls on average. Statistics enables us to ask whether the President’s tally of eighteen polls is large enough to reject the notion that the President is tied or behind in Nevada. The calculated statistic in the table above is 12.80. The column headed with “p” reports the probability that the race is tied. In this case there are only three chances in 10,000 the President actually trails in Nevada if he is leading in eighteen out of twenty polls.
Two other states besides Nevada also appear firmly in President Obama’s coalition, Wisconsin and Ohio. If the President does indeed win these three states, Ohio, Wisconsin and Nevada, and retain his leads in “leaning” states like Michigan and Pennsylvania, he will win precisely 271 Electoral Votes, or one more than he needs to gain re-election. Replacing Nevada with New Hampshire would leave the President one EV short at 269.
The bottom half of the chart replicates the same analysis using only polls taken since September 1st. The President is still a significant favorite in all three states based on just the more recent polling as well as all the polls since June 1st.