Friday, April 27, 2007

After a flurry of new polls in the last 24 hours, a new Harris poll taken 4/20-23/07 finds approval at 28%, disapproval at 70%. With this addition, the estimated approval trend stands at 34.1%.

The Harris result is a good deal below the estimated trend, and below other recent polls. In part this reflects a typical Harris "house effect". With it's atypical four point question format ("Excellent, good, fair or poor" rather than "approve or disapprove"), Harris' approval results are often a bit below that of other pollsters. The plot below, however, shows that this low result is not only due to house effects. The current poll is noticeably further below the trend estimate than are other recent Harris results.

How far the new poll is from the trend is apparent in the next figure below, in which Harris clearly falls outside the 95% confidence interval for "normal" variability. While it is possible the new poll at 28% represents a sudden negative shift, this is quite a distance away from other contemporaneous results from CBS News, NBC/WSJ and Pew.

In light of the outlier analysis, it seems likely that the new Harris poll does not represent a sudden shift in support for President Bush. It is more reasonable that our prior estimate of 34.7% is closer to the national mood, rather than the 34.1% resulting from inclusion of this poll. In either case, the overall picture of relatively little trend in the last 5 months holds. We have been in a period of approval moving up or down a point, but never establishing strong evidence for a trend. While it could change at any point, the post-2006 election period has so far held in rough equilibrium.

Thursday, April 26, 2007

We remain in a flat period. A one point improvement or a one point decline has been the story of the last five months. So far the President has managed to neither rally support nor to sink in public approval.

Wednesday, April 25, 2007

Today's little quote on Vice-President Cheney from Senate Majority Leader Harry Reid (D-NV) in the New York Times, "I’m not going to get into a name-calling match with somebody who has a 9 percent approval rating", was the second time in two weeks that a prominent Democratic Senator asserted that public support for the Vice-President is exceptionally low. On April 15, on Fox News Sunday, Senator Carl Levin (D-MI) said "Vice President Cheney has zero credibility. I don't think anybody more than 5 percent or 10 percent of the hardcore solid Republican base believes much that Vice President Cheney says. He has no credibility."

My colleague at Pollster.com, Mark Blumenthal, promptly set the current record straight with this post. Cheney's approval is running between 29% and 34% in the four most recent polls.

Normally I'd write either of these quotes off to hyperbole in a world rarely disciplined by details like data, but the two quotes in short order raises a more interesting question: do Democrats, even political professionals, systematically misperceive Cheney's standing in public opinion? It isn't that Cheney has a particularly positive public standing, but as the figure above shows, he in fact is only a few points lower in approval rating than is President Bush.

In the "paired-data" (meaning only polls that ask about both Bush and Cheney job approval) above, Bush approval is about 34% and Cheney approval is 32%-33%. Over the course of the entire administration, Cheney has consistently been a bit below the President in approval, more-so in the first term and less-so in the second term. This is partly an artifact of more people saying they "don't know" if they approve or disapprove of Cheney.

The 2004 reelection campaign represented a change, with the gap in "don't know" rates narrowing from double to single digits. This reduced the extent to which approval of Cheney was affected by lack of knowledge or opinion crystallization. Still, there remains a persistent gap in those unable to give an opinion on Bush and Cheney's job performance, and this contributes somewhat to the Bush-Cheney approval gap, keeping Cheney's approval below that of Bush.

On the disapproval side, the story is a bit more interesting. Cheney suffered greater disapproval than Bush in the first term, despite the difference in "don't know" rates. The 2004 election and the early 2005 period represents the turning point, with Bush moving modestly ahead in disapproval, a lead he has consistently held since mid-2005.

This disapproval difference is clearly not due to Cheney's greater obscurity-- he was more disapproved of when he was more unknown.

A couple of conclusions are clear. Cheney has consistently had a lower approval rate than Bush, but the margin since 2004 has not been large. A significant portion of this approval difference is attributable to the difference in "don't know" rates. As the latter shrunk, so the approval gap shrunk. Cheney was significantly more unpopular than Bush in the first term but that has reversed. Taken together, there is certainly no evidence that Cheney is significantly less popular than the President.

So why are Democrats so convinced that Cheney is substantially more unpopular than Bush, given the small actual differences? One possibility is the overwhelmingly negative views of Bush among Democrats (his approval rating among Democrats has been below 10% for months) means that Democrats move in a virtually completely homogeneous environment which gives them no chance to encounter other Democrats with a more positive view of Bush (and by extrapolation, Cheney-- I have no data on Cheney approval by party, but it is surely also below 10% among Democrats.) So when Sen. Reid says Cheney has a "9 percent approval rating" he might be reflecting the views of Democrats pretty accurately, even though he is wildly understating approval among the public as a whole.

And I don't discount the possibility that these comments were deliberate rhetorical exaggerations, and that both Sen. Levin and Sen. Reid are perfectly well aware of the data. Despite that caveat, the perception of Cheney in the Democratic blogosphere amply supports the notion that this perception that he is far less popular than Bush is in fact widespread and not just confined to these two Senators.

Tuesday, April 10, 2007

A large number of media outlets and blogs ran this AP story on congressional approval. USAToday carried it this way:

AP Poll: Congress' approval hits high point

Public approval for Congress is at its highest level in a year as Democrats mark 100 days in power and step up their confrontation with President Bush over his handling of the Iraq War, the issue that overshadows all others.

. . .

The findings from an AP-Ipsos nationwide poll provide a snapshot of public sentiment in the days after the House and Senate triggered a series of veto threats from the president by passing separate bills that provide funds for the war, yet also call for the withdrawal of U.S. combat troops.

Which is all well and good except the AP poll is quite high compared to other recent polls of congressional approval, including AP's previous polls.

Of the last six polls the three most recent have come in above the previous trend estimate of 30.8%: Gallup has it at 33% (up from their previous 28%), AP at 40% and the Hotline at 37%. (Gallup has done two of the last six, so appears twice in the figure below.) The effect of these new polls is to revise my estimate of congressional approval up to 33.1%. But that is still a good deal shy of the AP result at 40% and a bit south of Hotline at 37%.

With the addition of the three new polls, what had looked like a pretty steady downturn in congressional approval since January now looks pretty flat. For the Democrats, that's a definite improvement, but it certainly isn't the large upturn that the AP story (and its reverberations in the blogosphere) have taken it to be.

Notice in the figure above for the AP, that AP polling has generally tracked quite well with my trend estimate of congressional approval. Only this most recent poll is well above the trend, with all other AP polls hugging the blue line pretty tightly. So AP doesn't routinely produce high congressional approval numbers, just this time.

As always, one poll should not dominate our interpretation of political dynamics. In this case, it is possible that something dramatic has suddenly boosted congressional approval, and AP (with the Hotline a couple of days earlier) was just lucky enough to be in the field right after it happened. We can offer reasons why this may or may not be the case, though I prefer to just wait for more data to settle the case one way or another.

But what we can do is look at how the trend estimator varies, and how the polling varies around that trend. The plot below shows the blue trend line with a gray region representing the variation in that estimate from 30,000 "bootstrap" estimates. A bootstrap is a good way of estimating the variability of an estimator, especially as in this case when we don't wish to make strong assumptions about the statistical distribution of the variation. The gray region represents the range of estimates of congressional approval we might reasonably expect to see, given the randomness of the polls and of events that drive congressional approval. I've overlaid the actual poll results on top of this, in red, so it is clear how the estimator varies (the gray area) and how the polls vary (the red points) all around the estimated trend (the blue line).

So what do we see? Quite a bit of variation. Congressional approval is asked a good deal less often than is presidential approval, so with less data, the gray area is relatively wider than it is for presidential approval, especially early in the series when very few polls were available for the early 1990s. That's somewhat better now, and the range of the gray area is smaller now than at the beginning.

The other variation is the polls. They are distributed roughly equally above and below the trend line, and spread a little bit more than does the estimator's gray area.

And right at the end, you can see that the AP data point at 40% is at the extreme upper end of the range of plausible estimates.

This doesn't mean it is necessarily wrong, and it certainly doesn't mean the poll was flawed. ALL poll vary, and individual questions vary as well. It is perfectly normal to see this kind of range of variation, as looking at the spread of the other red data points clearly illustrates.

But before we write a headline about support for congress being at a new high point, it would be worth considering the evidence a bit more carefully. Judging from all the data we have in hand today, it would be rash to suggest that congressional approval is at 40%. A much more plausible estimate is where the trend estimator stands: 33.1%.

And that changes the interpretation of the story which plays on Congress at 40% vs Bush "in the mid-thirties". In fact, the best evidence as of tonight is that Bush is at 34.4% and Congress at 33.1%. Politically, that means neither has a clear edge in support over the other at the moment. (Caution: We should really look at approval of "the Democrats in Congress" if we want to directly address the question of which end of Pennsylvania Avenue enjoys more support in the coming struggle over the Iraq funding bill. And other questions too!)

One final caution is that the trend estimator is sensitive to the most recent polls. So these three new polls pulled the estimate up enough that what had previously looked like some modest decline since January now looks to be pretty flat. Is it? The graph below shows how sensitive the estimator is to each of the last 20 polls.

The results show that for much of the last 20 estimates, the trend has been moving down. That has only been arrested as the last three polls have been added. So any conclusion about whether congressional approval is declining, steady, or increasing, rests on the thin reed of just three polls. Before we reach bold conclusions about the trajectory of public support for Congress, we should take some strong caution pills, and look at each new poll with some healthy skepticism until it gives us reason to trust it.

The trend estimate of support for Senator John McCain for the Republican nomination continues to slip downward. This trend has been apparent for a while, but shows signs of accelerating rather than stabilizing. The new Gallup Poll taken 4/2-5/07 has McCain at 16%, and the Gallup release notes this is a decline from previous Gallup data. But the decline is more widespread than just a single poll by a single organization. Since January 1, Sen. McCain's support has been on a downward trajectory. This loss of popular support in national polls has come as Giuliani has moved steadily upward and other potential challengers (Gingrich and Romney) have seen modest, if steady, increases.

The finance performance of the McCain campaign raised questions about his support among significant Republican donors, but the continuing negative trend in popular support may prove more deadly. McCain is set to "re-launch" his campaign with a new round of speeches and appearances. The question is whether he can sell his support for the war (something Republicans should be receptive to) and his conservative record (generally strong) to an audience that despises his campaign finance reform bill and sees him as too much of a loose canon.

Were it not for campaign finance, which many conservatives hold bitterly against McCain, and perhaps his support for restrictions on interrogations, McCain should be able to appeal to Republicans, certainly more so than Giuliani. But so far little if anything seems to be working for McCain. If the relaunch fails, McCain's fall threatens to move Gingrinch into second place among Republicans nationally. (Or perhaps that should be Fred Thompson, at 10% in the new Gallup poll, but with too little polling yet for a trend estimate.)

Monday, April 09, 2007

A new USAToday/Gallup poll taken (4/2-5/07) finds approval at 38%, disapproval at 58%. With the addition of this datapoint the trend estimator stands at 34.4%.

The new Gallup poll is a good bit above the previous trend estimate of 33.8% and is exerting a noticeable pull on the trend, but the new poll is within the +/- 5 point confidence interval for polling around the trend estimate, so it does not qualify for outlier status. As any reader of these pages should know, there is considerable variability in polling, and Gallup's latest is clearly high but within that range.

Looking only at Gallup polls since the 2006 election, approval has averaged 35.2% in Gallup's readings. This has fluctuated between 32% and 38% with little discernible trend. The current reading then, is also consistent with the variability in Gallup's polling over the past five months.

While the trend estimate takes a twitch up with this new poll, the shift is well within the range of noise around the estimator. My estimate has suggested that approval has held relatively steady between 33% and 35% since 1/1/2007. Until several more polls join Gallup in the high 30s, the best bet remains between 33% and 35%.

Wednesday, April 04, 2007

(Click once or twice on the graphic for a full resolution view. It is big.)

The Democratic congress was swept into office due in part to the low approval of the old Republican congress. Initially approval of Congress improved but is now beginning to slide down a bit. With a confrontation on Iraq war funding looming, it is time to take a look at congressional approval.

As of polling completed 3/28/07, approval of Congress' handling of its job is at 30.8%, compared to 33.3% for President Bush. But Americans love to hate Congress even as we usually love our district's member of Congress. So how does the current 30.8% approval compare with the past?

Over the long haul, from 1990, current approval is rather low, though not at rock bottom. Congressional approval bottomed out in 1992 during the House banking scandal in which members were allowed to maintain negative balances in their accounts. While trivial in comparison to national policy issues, this scandal was a potent symbol of congressional privilege and members who had bounced checks were seriously affected in the 1992 elections. Of the 47 members who bounced over 100 checks, 55% (26) were gone from the 103rd Congress in 1993. Even among those with less than 100 bounces the turnover rate was 43% higher than among those with no check problems. (Data from Jacobson and Dimock, American Journal of Political Science, August 1994, pp 601-624.)

At the low point, my estimate of congressional approval fell to an almost unbelievable 17.5% on June 7, 1992.

Approval improved in 1993 and the first half of 1994, but stayed mostly in the 20s, breaking 30% briefly in early 1994. But this small improvement was followed by another substantial collapse during the fall campaign, to 23.8% by election day. By comparison, in 2006 congressional job approval was at 27.5% on election day.

Following the 1994 Republican revolution, approval improved significantly for the first half of 1995, topping 35% for the first time since early 1990. However, this improvement reached its limit as the Republican Congress confronted a Democratic president over budget decisions. With the confrontation and the eventual shutdown of the federal government, congressional job approval turned down to the high 20s again, bottoming out as the budget crisis was eventually resolved.

Congress then enjoyed two and a half years of improving public approval. Interestingly, this occurred despite a Democratic president whose popularity was also increasing during this time. Approval reached 50% in early 1998, and remained there until after the 1998 elections.

But impeachment was a mistake, at least from the perspective of approval of Congress, with approval dropping sharply by some 7 points during and immediately after the impeachment proceedings. Congress remained below 45% until once more improving to 50% approval during the 2000 election contest.

As with presidential approval, 9/11 produced a significant upturn in congressional approval, though this fell back to around 47% by the 2002 elections.

The start of the Iraq war saw a substantial increase in approval of President Bush, but there is no evidence of a similar rally for Congress in early 2003. From 2003 through the 2004 elections, approval slowly declined to about 40% before turning up slightly at the end of 2004.

That was the last good news for congressional approval under Republican control. The spring of 2005 saw a very sharp drop in approval, from 41% to 33% in the first half of the year, followed by a slower but steady decline until mid-2006. Approval finally bottomed out around April 2006, and held relatively steady through the election, ending at 27.5% on election day.

With the start of the 110th Congress in January, the Democrats enjoyed a modest, but nonetheless significant upturn in approval, to 32.6%.

Since then, the trend has been slowly but steadily downward, reaching the current 30.8% approval as of March 28th.

Compared to 1994, the Democratic gain has been modest. Following the 1994 election, the new Republican Congress enjoyed an immediate upturn of over 7 points. The improvement peaked at 35.9% approval on March 30, 1995. The current Democratic gain was limited to 5.1%, and has since declined rather than continued to improve, as in early 1995.

And so we come to the first major confrontation of a president at 33.3% approval and a Congress at 30.8%. Given the results from 1995, a Congress should worry about confronting even an unpopular president. On the other hand, the budget battles of 1995 were quite different from the Iraq policy battles of 2007. President Bush seems to be betting that a cut off of funds, or even a temporary lapse of funding, will redound to his benefit. But recent polls have also found that more of the public support a withdrawal deadline than take the President's position. How this issue is shaped (starting a withdrawal versus cutting off the troops in the field) will have a significant effect on the outcome of the public debate. But it is a debate in which neither of the primary actors have a substantial advantage in public approval.

(I should note that ratings of "Democrats" or "Democratic leaders" in Congress are a bit above those of Congress as a whole, the variable of interest here. In the few polls that have asked about Democrats or Democratic leaders since the new Congress started, the approval ratings have mostly been in the low 40s, with one poll above 50. This is relevant to the debate over Iraq, and I will turn to this element of evaluation in a subsequent post.)

A slightly stale Zogby poll taken 3/22-26/07 has approval at 32% and disapproval at 67%. The poll released results for other items, but the approval item did not appear until 4/3 on Hotline. With this result added, the approval trend stands at 33.3%.

Zogby tends to run below the trend, though in this case by only a small amount.

A Newsweek poll taken 3/28-29/07 finds approval at 33%, disapproval at 60%. With this addition the approval trend estimate now stands at 33.5%.

The Newsweek poll, which often comes in with a below trend house effect, is very close to trend, so has little impact on the estimate. We've now seen several polls in the 33%-34% approval range, plus one at 37%.

The trend estimate has remained between 33% and 35% approval over the last 20 polls. While there appears to be a consistent but small negative slope in approval since the November elections, the rate of change is small enough that it has been hard to distinguish from stable approval. Individual polls, with a margin of error around 5 points about the trend estimate, cannot hope to reliably detect such a small rate of change. Even the trend estimate, with an uncertainty of about +/- 2 points is hard pressed to unequivocally call the current period a downward trend, though the bootstrap plot shows a small downtrend is a pretty good bet.

It is interesting that approval has not suffered a sharp downturn in the aftermath of the November elections and the Democratic takeover of Congress. Rather, it appears that public dissatisfaction with President Bush largely spent itself in the elections. Since then, the new opposition between Republican President and Democratic Congress appears to have stabilized opinion of Bush's handling of his job. As we saw in yesterday's presidential comments on funding for Iraq, the Democratic Congress provides a target for Presidential rhetoric which was lacking when Republicans controlled the Congress. The struggle over the emergency funding bill will provide an interesting lesson in the relative strengths of President and Congress.

The residuals remain well behaved, so no recent polls are currently "outliers".

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About Me

I am co-founder of Pollster.com and founder of PollsAndVotes.com.
I am also a professor of political science at the University of Wisconsin, where I teach statistical analysis of polls, public opinion and election results. Data visualization is central to my approach to analysis.
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