Poll Analysis: Three polls in the Washington gubernatorial race

In the past several days, three new polls have been released that weigh in on the Washington state gubernatorial race. In all three polls, former Congressman Jay Inslee (D) leads state AG Rob McKenna (R) by narrow margins—always within the margin of error. This post will look at the three polls separately, and then combine them into a joint analysis.

Late last week, the second wave of the Washington Poll was released. The poll surveyed 632 likely voters (MOE 3.9%) using live interviews taken from the 18th to the 31st of October. It found Inslee leading McKenna by 48.7% to 45.6%.

A Monte Carlo analysis consisting of a million simulated elections found that Inslee won 708,884 times to McKenna’s 281,485 wins. In other words, this poll suggests that Inslee would win the election now with a 71.5% probability, and McKenna would win with a 28.4% probability.

Here is the distribution of election outcomes from the analysis:


The other poll released late last week was from Survey USA for KING 5. The poll of 555 likely voters (MOE 4.2%) was taken from the 28th to the 31st of October. It found Inslee leading McKenna by 47% to 46%.

A Monte Carlo analysis of just this poll finds Inslee winning 561,944 times and McKenna winning 425,662 times. The results would suggest that Inslee would win the election now with a 56.9% probability to McKenna’s 43.1% probability:


The final poll, released just yesterday, is from PPP. The poll surveyed 932 likely voters (3.2% MOE) from November 1 to 3, and found Inslee leading McKenna by 50% to 48%.

In the Monte Carlo analysis of the PPP poll results, Inslee wins 663,870 times and McKenna wins 327,401 times. This poll, alone, puts Inslee’s chances of winning an election now at 67% to McKenna’s 33% probability:


We can jointly analyze the three polls together. Our “meta-poll” has a total of 2,119 “voters” of which 2,025 offered a preference for Inslee or McKenna. Inslee took 1035 (48.8%) of these votes, and McKenna took 991 (46.8%) votes. There were 93 (4.4%) undecideds.

The Monte Carlo analysis gives Inslee wins 751,986 times, and McKenna wins 243,119 times, suggesting that, in an election held now, Inslee would win with a 75.6% probability and McKenna would win with a 24.4% probability:


Finally, lets look at the polling trajectory over the past 6 months:


Inslee took over the lead in late summer, and appears to have held a modest lead through September. Since then, the race has tightened considerably, and we see Inslee with the slightest advantage over the last two months.

This one will be close, but the three most recent polls combine to give Inslee a slight edge.


  1. 1


    It may be that I don’t watch the “right” TV channels, but it appears to me that the number of McKenna ads and anti-Inslee ads (from Rove, the Chamber of Commerce, and other such evil spawn of Citizens United) has increased dramatically in the last several days.

    I find that an odd strategy, since historically Washington ballots counted after Election Day are always more Democratic than early ballots. If anything, I think those scurrilous ads would be more likely to galvanize the Democrats in opposition to these incessant, despicable attack … to motivate Dems who might otherwise have skipped races other than Obama-Romney into casting their Inslee (and Ferguson, since the outside slimers are attacking him too) votes.

    But what do I know?

  2. 2

    Real American spews:

    @1 , Good. I love seeing wealthy people throwing their money away. It is the only way to shake their ill-gotten gains from their Cayman island accounts. It’s is the only way they actually end up creating jobs, albeit in the advertising and media business.

  3. 4

    proud leftist spews:

    I’ve kept my calendar clear this week. I suspect that good D lawyers in this state may need to be summoned quickly to combat Republican voting fraud. I can’t believe the voting vans those fraud artists are parking in King County mall parking lots.

  4. 5

    Liberal Scientist is a Dirty Fucking Socialist Hippie spews:

    I can’t believe the voting vans those fraud artists are parking in King County mall parking lots.

    WHAT??!! Link? What’s the story?

  5. 6

    Roger Rabbit spews:

    @4 The D’s are deploying lawyers to voting locations and auditors’ offices all over the state on election day.

  6. 9


    I saw one of those vans at the Factoria Mall yesterday. If I didn’t have my son in tow, I would’ve stopped to investigate what the hell that was all about. Is that where they’ve been trying to collect ballots?

  7. 10

    Roger Rabbit spews:

    @4, @9 On their website, King County GOP describes the vans as “an advanced Get-Out-The-Vote operation” and says they “serve Republicans of the surrounding community looking for information about Republican endorsed candidates and assistance in returning their ballots.”


    I don’t see anything illegal about that, as far as it goes, but I’m curious what “assistance in returning ballots” consists of in actual practice.

  8. 11

    Carl Berard spews:

    Good Bye – Christine…….

    Alot of People will Miss You…………

    I am Now Hoping For The Best for Washington State