Strategic Vision has released a July poll that includes the Washington state gubernatorial contest. The poll shows Gov. Christine Gregoire (D) leading challenger Dino Rossi (GOP-Party) 47% to 45%, with 8% “undecided”. The poll of 800 people was taken from July 25th to July 27th, and has a margin of error of 3.5%
This is the fourth July poll in this race. Here are the results from the four polls:
|Poll||Start||End||# Polled||MOE||% Gregoire||% Rossi|
Rossi last led in this race thirteen polls ago, back in late February.
I’ll do two Monte Carlo analyses. First is an analysis of the poll numbers in the new Strategic Vision poll in order to estimate the probability that Gregoire (and Rossi) would win an election held right now. I simulated a million gubernatorial elections of 800 voters each, where each voter had a 47% chance of voting for Gregoire, a 45% chance of voting for Rossi and a 8% chance of voting for neither.
Result 1: Gregoire won 716,473 of the simulated elections and Rossi won 271,349 times. This suggests that, in an election now, Gregoire would have a 72.5% probability of winning and Rossi would have a 27.5% probability of winning. A statistician would point out that Gregoire’s lead in this poll is within the margin of error (i.e. her probability of winning is less than 95%).
Here is a plot showing the distribution of votes in the million elections (blue bars are wins for Gregoire and red bars are Rossi wins):
The second analysis combines the polls from all four polls in the Table, to give a July score for this race.
The combined polls yield a pool of 1127 (47.6%) votes for Gregoire, 1061 (44.9%) votes for Rossi, and 177 (7.5%) who voted for neither. Again, I simulate 1,000,000 elections.
Result 2: Gregoire won 919,335 of the simulated elections and Rossi won 77,493 times. The results suggest that, if a July election were held, Gregoire would have won with an 92.2% probability, and Rossi would have won with a 7.8% probability.
Here is a plot showing the distribution of votes in the million elections for the combined polls:
Strategic Vision also polled for the presidential election in Washington state. Sen. Barack Obama (D) leads Sen. John McCain (R) by a +11% margin, 48% to 37%. Obama’s lead is well outside the margin of error for this poll.