I posted the results earlier today of the Washington Senate race based on KPLU’s news reports. At noon today, the KCTS/KPLU/Washington Poll top lines were released for public consumption.

In that all-important race between the single most powerful mom-in-tennis-shoe in the Senate & nation, Sen. Patty Murray (D-WA), and the single most sought-after motivational speaker on the foreclosure profiteering seminar circuit, Dino Rossi (R), we find Sen. Murray leading 50% to 42%. This makes five polls in a row that has Murray in the lead.

This poll surveyed 500 people from October 5th to the 14th. Hence, it overlaps every one of the other five October polls. Here is summary of all the polls this month:

	Start	End	Samp.		%	%	%
Poll	date	date	size	MOE	Murray	Rossi	Diff
WA Poll	05-Oct	14-Oct	500	4.3	50	42	D+8
SurveyUSA	11-Oct	14-Oct	606	4.1	50	47	D+3
CNN/Time/OR	08-Oct	12-Oct	850	3.5	51	43	D+8
Elway	07-Oct	11-Oct	450	4.6	51	38	D+13
Fox	09-Oct	09-Oct	1000	3.0	47	46	D+1
Rasmussen	06-Oct	06-Oct	750	4.0	46	49	R+3

What does this poll tell us by itself? A Monte Carlo analysis using the observed sample size and percentages gives Murray 902,830 wins to Rossi’s 92,001 out of a million simulated elections. That is, the poll provides evidence that Murray would have a 90.8% probability of beating Rossi in an election held now.

But we can pool the results from all six of the polls shown in the table. This gives us a total of 4,156 “votes”, of which 3,890 of them go to either Rossi or Murray. Murray gets 48.9% to Rossi’s 44.7% (or, if we look at just the votes for Murray and Rossi, Murray is up 52.2% to 47.8%). A simulation analysis finds Murray beating Rossi with 975,049 wins to his 24,332 wins.

The new KCTS/KPLU/Washington Poll has added a bit more certainty to Murray’s lead. Yesterday, this same analysis using all but today’s poll gave Murray a 94.5% chance of winning. Today, with six polls, we find that Murray would have a 97.6% chance of beating Rossi in an election right now.

Finally, let me address a meme about this race that has been quite prevalent in the recent media. There is an idea the the polls are “all over the place.” Maybe. But not really. Let’s look at results of polls taken in September and October:

Since these polls are taken on a sample of the underlying voting population, there is some uncertainty about the results. The vertical bars on the poll results show the plausible range that the voting population could have, given the margin of error inherent in the poll. (Other problems can lead to biased estimates; the margin of error only incorporates uncertainty reflecting the size of the sample.) And even then, by chance, we expect the true value to lie outside of the plausible range in about one in twenty polls.

Looking at the recent polls, it seems the last five polls mostly overlap, suggesting that the truth lies somewhere near a 54% Murray, 46% Rossi result. We also see this in early September. From mid-September to early October, Murray appears to do significantly worse.

Remember the discussion with the Elway poll last Tuesday? Elway was compelled to justify his noticeably higher numbers for Murray, and suggested that there was a difference between robopolls and live-interview polls. (Of course, if we consider the plausible range, the Elway poll fits right in.) The polls released since Tuesday support Elway’s suggestion.

Elway did not offer a hypothesis why robopolls would turn in different results than the live-interview polls, but I did. Via Goldy:

As Darryl suggested the other night at Drinking Liberally, what if the enthusiasm gap we’ve all been hearing about is largely manifested in who is or is not willing to give up ten minutes to interact with an automated poll? I know I’ve hung up on a couple robo-polls this year, but find it harder to do so with a real live person. Interesting hypothesis.

This looks right for all the recent polling. We see that the three live-interview polls (Elway, WA poll, and CNN) all post numbers on the high side and the robopolls (SUSA, Rasmussen and FOX News) all come in on the low side. That big dip in the middle is formed from six robopolls taken in a row. In fact, Rasmussen and FAUX News both use the same company—Pulse Opinion Research–to do their polling. It may not be chance that FOX New and Rasmussen both give Murray her worse performance in this series. And this would explain the question I posed in August, “What the hell happened to Survey USA?”

The robopoll/live interview/enthusiasm gap hypothesis was offered Tuesday before the three most recent polls were released, and I am now pretty confident that this is what is happening in the Murray—Rossi race here in Washington.

I am less confident about other House and Senate races nationally, but if it can happen here, it might well be happening elsewhere. I think there is a fair possibility that robopolls will systematically underestimate the performance of Democrats nationwide, which will make for a pretty darned interesting election night!

(Cross posted at Hominid Views.)

KPLU is reporting that a new poll in the Washington senatorial race will be released today from The Washington Poll. The poll shows Sen. Patty Murray (D) leading real estate opportunist cum foreclosure seminar motivational speaker Dino Rossi (R) by 50% to 42%.

The sample size is 500 giving a margin of error of 4.3%. I’ll provide a more detailed analysis when the poll results are released.

The Washington poll is made using live calls (like Elway). This poll differs from most other polls in this race in that the results are of registered voters, rather than likely voters. The poll was sponsored by KPLU and KCTS-9 and conducted by the University of Washington out of the Political Science Department. (In the interest of full disclosure, I work for the UW; however, I have nothing to do with this poll.)

Yesterday I alluded to a new Survey USA poll that I thought would be released in a day or two for the Senate race between Sen. Patty Murray (D) and foreclosure seminar motivational speaker Dino Rossi (R). Well…it happened today.

The new poll has Murray leading Rossi, 50% to 47% from a survey of 606 likely voters taken from 22 October to 14 October. The margin of error is 4.1%.

This is the fourth poll in a row that has Murray leading Rossi. In fact, over the past month, there have been nine polls in this race (not including those released by the candidates or political parties). Murray has led in seven of the nine polls. Yeah…Rossi has a pair, but they are really pretty tiny (+1 and +3) compared to Murray’s (+3, +7, +13, +1, +1, +2, +5).

A Monte Carlo analysis of the SurveyUSA poll gives Murray 699,651 out of a million simulated elections. Rossi wins 290,266 times. In other words, in an election held now, Murray would have a 70.7% chance of beating Rossi, given the evidence offered in this poll. Here is the distribution of simulated election outcomes:

We now have five polls taken in October (the earliest poll was from Oct 6). Let throw them together for a better picture of the evidence. The five polls yield 3,656 “votes” of which 3,430 are for one of the candidates. Murray gets 1,781 “votes” (48.7%) and Rossi, 1,649 (45.1%). From the simulated elections, Murray wins 943,548 times; Rossi wins 55,016 times. Thus, the October polls, taken as a whole, support the idea that Murray would win with a 94.5% probability in an election held now. Here is the picture:

I’ve now written about new polls in this race for five days straight. If tomorrow bring us another poll then we can declare it WAPollpalooza week. And then maybe I can get some rest on the seventh day….

Yesterday we had a new Elway poll in the senatorial race between Sen. Patty Murray (D) and real estate opportunist Dino Rossi (R).

Today there is a new CNN/Time/Opinion Research poll weighing in on the race. The poll of 850 likely voters, taken from October 8 through 10, has Murray leading Rossi 51% to 43%. The margin of error is 3.5%. This result is pretty similar to yesterday’s Elway poll.

A Monte Carlo analysis consisting of a million simulated elections at the observed preferences in this new poll has Murray winning 954,664 times and Rossi winning 42,982 times. The evidence from this latest poll suggests that, in an election held today, Murray would win with a 95.7% probability; Rossi with a 4.3% probability. Here is the distribution of outcomes from the simulated elections:

But I missed another poll that was released on Monday or Tuesday. A FOX News poll taken on 9 Oct on a sample of 1000 individuals found Murray with a 47% to 46% lead over Rossi (3% margin of error). Thus, there have been a total of four polls published in October and Murray has led in the last three—Rossi last led in a 6 Oct Rasmussen poll.

Given that all four of these polls were taken either consecutively or over overlapping days, we can combine them for a better picture of how this race is shaping up over the the second week of October. The four October polls give a total of 3,050 responses, of which 2,842 went to either Murray or Rossi. Murray got 1,478 ( 48.5%) and Rossi got 1364 ( 44.7%). A Monte Carlo analysis gives Murray 934,835 wins to Rossi’s 63,503 wins.

Thus, the four polls combined provide evidence that an election held over the past week would go Murray’s way with a 93.6% probability, and would go Rossi’s way with a 6.4% probability:

A look at the polling to date suggests that Murray’s September slump has ended; she has clearly retaken the lead and it seems to be her strongest lead to date.

This is definitely a good position for Murray to be in during the week that ballots drop. The next couple of polls will be telling, and I think we’ll have new polls from Survey USA and the Washington Poll within a few days, so stay tuned….

(Cross posted at Hominid Views.)

As is our custom, Tuesday brings us together for an evening of politics under the influence. Please join us at the Seattle chapter of Drinking Liberally at the Montlake Ale House, 2307 24th Avenue E. beginning at about 8:00 pm. Stop by earlier for dinner.

Not in Seattle? There is a good chance you live near one of the 249 other chapters of Drinking Liberally.

A new Elway poll has just been released for Washington state. Included in the poll is a head-to-head match-up in the Washington state senatorial race between Sen. Patty Murray and real estate salesman Dino Rossi. The poll was conducted using live interviews between October 7 and October 11 on a sample of 450 likely voters. The margin of error is 4.6%.

The results have Murray leading Rossi by 51% to 38% with “leaners” excluded. Murray does even better (55% to 40%) if “leaners” are included. I’ll stick with the former numbers in what follows. Here is the polling in this race to date (excluding polls released by the campaigns):

This new poll reverses a not-so-good trend for Murray over the past month. Her lead had the appearance of slipping away (although really the recent polls have all been a statistical tie).

You may also notice that all four of the Elway polls are more favorable for Murray than nearly all other polls. As Goldy mentions, Elway goes to some effort to explain this discrepancy. Elway shows that there are distinctly different trends for polls done using automated questions compared to live interviews. The robopolls showed Rossi with a slight lead early in the year with the trend lines converging to a tie right now. The live polls showed Rossi and Murray tied early on, with Rossi staying relatively flat and Murray pulling away by about 7 points. No explanation is offered, but the implication is that Elway’s live polls are more accurate.

We can, to some extent, evaluate Elway’s hypothesis. Here is a graph I published on Nov 3, 2008, when Dino Rossi was running against Gov. Christine Gregoire in the Washington state Gubernatorial race:

Here again, Elway seemed to favor Rossi’s opponent relative to other polls, suggesting Murray would win 51% to 39%. The Washington Poll, another live interview poll, was also on the high side relative to other polls earlier (51.4% to 45%) and close later (50% to 48%). In the last month most pollsters had the race within two points: Strategic Vision (50% to 48% and 49% to 47% earlier), Rasmussen (50% to 48%), and SurveyUSA (50% to 48% and 48% to 47% earlier). The day after this graph was made, SurveyUSA released their final poll (52% to 46%).

The final tally in the Gregoire–Rossi race was 53.2% to 46.8% (+6.4). SurveyUSA’s last poll nailed it (+6), and the Washington Poll got the spread right (+6) in their earlier poll. Elway underestimated both candidates’ percentages and had a high spread (+12). This suggests that most of the recent polls underestimate Murray’s performance, even if the Elway poll probably overestimates it.

Back to the Elway poll…As usual, I’ll analyze it using simulated elections of 450 likely voters voting at the observed percentages in order to make a probability statement about who would win in a hypothetical election held now. From a million such simulated elections, we find that Murray wins 979,930 times and a Senator Rossi happens 18,537 times. In other words, this poll gives Murray 98.1% chance of winning an election right now. Rossi’s probability is 1.9%. Here is the distribution of outcomes from the simulated elections:

Compare today’s picture to that from last Friday’s Rasmussen poll. In fact, since the Rasmussen poll was conducted on October 6 on a sample of 750 likely voters. It showed Rossi leading Murray 49% to 46%. Given that the Rasmussen poll was taken the day before the Elway poll started, it seems reasonable to combine ’em.

The combined Elway-Rasmussen poll sampled 1,200 likely voters of which 1113 chose one or the other candidate. Murray got 574 votes (47.8%), and Rossi got 538 (44.8%). A Monte Carlo analysis using a million simulated elections gave Murray 772,311 wins to Rossi’s 221,338 wins. In other words, these two polls combined suggests that Murray would have a 77.7% of beating Rossi if the election was held now.

To summarize, in combining the only two October polls to date—one done with live calls one by robocalls—Murray still comes out ahead, albeit not with a statistically significant lead.

(And there are 50 more clips from the past week in politics at Hominid Views.)

Tuesday brings us together for another evening of politics under the influence. Please join us at the Seattle chapter of Drinking Liberally at the Montlake Ale House, 2307 24th Avenue E. beginning at about 8:00 pm. Stop by earlier for dinner.

The Colbert Report	Mon – Thurs 11:30pm / 10:30c
The Word – It’s a Small-Minded World
www.colbertnation.com
Colbert Report Full Episodes 2010 Election March to Keep Fear Alive

Not in Seattle? There is a good chance you live near one of the 249 other chapters of Drinking Liberally.

(And there are links to some 40 more videos from the past week in politics at Hominid Views.)

Rasmussen released a new poll today in the race between Sen. Patty Murray (D-WA) and real estate opportunist Dino Rossi. The poll of 750 likely voters, taken on 28 Sept 2010, has Rossi (R) up by 1% (48% to 47%). If we consider this the only poll of relevance, a Monte Carlo analysis can suggest the probability of each candidate winning in a hypothetical election held today. From a million simulated elections of 750 people voting for each candidate probabilistically at the observed frequencies, we find that Murray wins 416,583 times and Rossi wins 573,402 times. That is, the best evidence from this poll suggests that, in an election held today, Murray would win with a 42.1% probability and Rossi would win with a 57.9% probability. Here is the distribution of outcomes from those million simulated elections:

Kind-of scary stuff, huh?

An interesting thing about the Rasmussen poll is that the actual polling work is done by a company called Pulse Opinion Research, LLC. As it happens, this is the same firm that did a FOX News poll just three days earlier. That poll of 1,000 likely voters taken on 25th of September had Murray leading Rossi 48% to 47%. There may some be differences in the likely voter model preferred by Rasmussen and Fox, but such an explanation isn’t really necessary to explain the differences. There is nothing at all inconsistent between the polls. Given the sample sizes, the polls do not really differ. Rather, they suggest that the race is close. We can pool the two polls to get a better idea of the race according to the methods used by Pulse Opinion Research. A Monte Carlo analysis using a sample size of 1,750 “voters” and pooled candidate preference percentages gives Murray 513,406 wins to Rossi’s 479,748 wins. In other words, the two polls taken by Pulse some three days apart suggests that, in an election held over the past week or so, Murray would win with a 51.7% probability.

But why restrict ourselves to a single pollster? In the past two weeks, there were four polls taken. The earlier two polls were by Survey USA giving Murray a 50% to 48% lead over Rossi in a sample of 609 likely voters taken from 19-21 Sept, and an earlier Rasmussen poll (750 likely voters) taken on 14th Sept, showing Murray leading Rossi 51% to 46%. When we pool these four polls, we get a respectable sample size of 3,109 individuals of which 2,987 went for either Murray or Rossi. Of these, 1,520 ( 48.9%) were for Murray and 1,467 ( 47.2%) were for Rossi. After a million simulated elections, Murray won 743,815 times and Rossi won 251,927 times. In other words, the combined evidence from four polls taken by two polling firms over the past two weeks suggests that Murray has a 74.7% probability of beating Rossi.

Does this reflect a decline in Murray’s support? I think it does a little. As this graph shows, the four most recent polls all fall within each other’s margin of error:

But the next two earlier polls, by CNN/Time/Opinion Research and Elway showed a significantly better lead for Murray than this most recent poll does, suggesting that there has been a real decline for Murray from a month ago. Alternatively, it could be just bad luck of the draw in Rasmussen’s most recent poll, since other than the most recent poll, all of the previous five polls fall within each others margins of error. So which is it? Hey…I report, you decide.

A new FOX News poll released on Tuesday shows Sen. Patty Murray (D-WA) leading real estate speculator and perennial candidate Dino Rossi (who prefers the GOP Party) by 48% to 47%.

You read it right…Murray leads Rossi in a FOX News poll. The poll surveyed 1,000 likely voters in Washington state on 25th of September.

This is the fifth consecutive poll that has Murray ahead of Rossi, and she has now led in seven of the last nine polls taken over the past two months. Elsewhere I take a closer look at the polls and its implications.

Another Tuesday, another evening of insightful political conversation, confabulation, consultation, and colloquy…under the influence. Please join us at the Seattle chapter of Drinking Liberally. We meet at the Montlake Ale House, 2307 24th Avenue E. beginning at about 8:00 pm. Stop by early for dinner.

Not in Seattle? There is a good chance you live near one of the 247 other chapters of Drinking Liberally.

Another poll has been released in the race between real-estate salesman and two-time gubernatorial race loser Dino Rossi (R) and Sen. Patty Murray (D). The Survey USA poll has Murray leading Rossi 50% to 48%. The survey included 609 likely voters.

As has been noted for their previous polls, something is “off” with Survey USA for this race. N in Seattle (among others) noted their “Metro Seattle” crosstabs were abnormal in the previous poll. Goldy thinks they’re still not quite realistic.

As usual, I’m interested in what the poll has to say about who would win in an election held now. Following a million simulated elections of 609 individuals voting at the proportions observed, Murray wins 635,301 elections and Rossi wins 353,991 times. In other words, this poll provides evidence that Murray would have a 64.2% probability of beating Rossi right now. Here is the distribution of outcomes:

With this new poll today, we have had a total of four polls taken in September:

	Start	End	Samp		%	%	%
Poll	date	date	size	MOE	Dem	Rep	Diff
SurveyUSA	19-Sep	21-Sep	609	4.1	50.0	48.0	D+2.0
Rasmussen	14-Sep	14-Sep	750	4.0	51.0	46.0	D+5.0
CNN/Time/OR	10-Sep	14-Sep	906	3.0	53.0	44.0	D+9.0
Elway	09-Sep	12-Sep	500	4.5	50.0	41.0	D+9.0

Murray has led in all four of these polls. In fact, she has earned at least 50% in each of the last four polls.

If we pool the respondents from all four September polls, we get a sample of 2,765 voters of which 2,658 went for either Murray or Rossi. Murray leads in the pooled sample 51.2% to 44.9%. Another Monte Carlo analysis gives Murray 991,344 wins to Rossi’s 8,375 wins. The evidence of these four polls indicate that Murray would have a 99.2% chance of beating Rossi in an election held this month.

Finally, here is the complete polling history for this race:

At this point, we can no longer debate whether or not Murray is vulnerable—there just isn’t much evidence for that. Perhaps the debate should turn to whether or not she will defeat Rossi by a single-digit or double-digit margin. Discuss.

It’s Tuesday, which means it’s time for an evening of some politics under the influence. Please join us at the Seattle chapter of Drinking Liberally. We meet at the Montlake Ale House, 2307 24th Avenue E. beginning at about 8:00 pm. Stop by early for dinner.

Not in Seattle? There is a good chance you live near one of the 247 other chapters of Drinking Liberally.

As I briefly mentioned earlier today, we got a new Rasmussen Poll in the race between Sen. Patty Murray (D) and Dino Rossi (R). The poll shows Murray leading Rossi 51% to 46%. The poll surveyed 750 likely voters on the 14th of September.

With this new poll, we have now had seven polls taken (and released to the public) over the past month:

	Start	End			%	%	%
Poll	date	date	Size	MOE	D	R	Diff
Rasmussen	14-Sep	14-Sep	750	4.0	51	46	D+5.0
CNN Time OR	10-Sep	14-Sep	906	3.0	53	44	D+9.0
Elway	09-Sep	12-Sep	500	4.5	50	41	D+9.0
Rasmussen	31-Aug	31-Aug	750	4.0	46	48	R+2.0
DSCC	28-Aug	31-Aug	968	—	50	45	D+5.0
SurveyUSA	18-Aug	19-Aug	618	4.0	45	52	R+7.0
Rasmussen	18-Aug	18-Aug	750	4.0	48	44	D+4.0

In what follows, I’ll ignore the DSCC poll. Not that I have any reason to doubt the poll. Rather, the poll was specifically released because the results favored Murray, thus clearly violating a statistical assumption used for the analysis.

Murray leads in four of the remaining six polls. As usual, I’ll begin with a Monte Carlo simulation analysis of the most recent poll (FAQ). Taking just the new Rasmussen polls there were 728 respondents who went for Murray or Rossi. Following a million simulated elections, Murray tallies 835,577 wins to Rossi’s 158,253 wins.

The evidence offered by this most recent poll suggests that Murray would have an 84.1% chance of beating Rossi if an election had occurred two days ago. Here is the distribution of outcomes from the simulated elections:

With three polls released over three days, we might as well combine all of ’em. Of the total of 2,156 individuals sampled, 2,061 go for Rossi or Murray. Murray gets 51.6% and Rossi gets 44.0% of the “votes.” The simulation analysis gives Murray 994,327 wins to Rossi’s 5,404 wins.

Thus, these three polls offer evidence that Murray would have a 99.5% chance of beating Rossi in an election held over that past week.

Rossi does a little better if we combine the last month of polls (all but the DSCC poll in the table). Now we end up with a sample of 4,274 respondents, of which 4056 are for Murray or Rossi. The raw percentages are 49.0% Murray and 45.9% Rossi. The Monte Carlo analysis gives Murray 933,103 wins to Rossi’s 65,250 wins.

If the past month of polling is representative of Washington state voters, the evidence suggests that Murray would win an election held now with a 93.5% probability.

Going back a month or two things did not look nearly so rosy for Murray. This is clear from a graph of the polling in this race:

See that dip that occurs over the summer? When the early September Rasmussen poll came out showing Rossi leading Murray 48% to 46%, I offered a theory:

There is another reason I am not (yet) too concerned. August 31 is still in the “dog days of summer” around here. In my many years of following polling in Washington state, I’ve learned that Washingtonians become very negative in the summer, only to perk right back up in the fall. I can’t really explain it…I’ve just observed it in approval numbers. Murray probably gets the worst of if from the summer malaise. That is, Murray doesn’t really have to worry about close results like these for another month….

I’m such a pessimist…it only took a couple of weeks.

(Cross posted at Hominid Views.)