Saturday, October 07, 2006

Bush Approval: Newsweek 33%

A new Newsweek poll finds approval of President Bush at 33%, a record low for the Newsweek organization, though not for other polls. The poll, taken 10/5-6/06 also found disapproval at 59%. As the graph above makes clear, however, the Newsweek poll is far below other recent polls and the current trend estimate. Before concluding that approval has "really" fallen to 33%, a good deal more data will have to confirm this extremely large drop.

That is not to say that approval has not turned down. Indeed, after the last two weeks of unremitting bad news for the White House, it is hard to imagine how if could have failed to do so. The question is whether the Newsweek poll is a reasonable estimate of current opinion or if it is too far away from other results to be plausible.

With the addition of the Newsweek poll, my current estimate of approval (the dark blue line) stands at 39.4, a full point below the recent high of 40.4 on 9/20. (This value is constantly being revised as new polling allows better estimates of the peak. On 9/19 the estimate was 41.1, while on 9/21 it stood at 41.2. Three polls completed 9/25-9/27 agreed on 42%, driving the estimator that day to 42.2. However, in light of all the polling since, the revised estimate puts the recent high at only 40.4 as of 9/20.)

While a one point drop may seem small, this is a drop in the trend estimate, NOT the very noisy raw polls which move by much more from poll to poll but which also contain much more random variation. One point in 16 days is almost 2 points per month, which is quite a substantial rate of decline. For comparison, during the first five months of 2005, the President's approval declined by one point each 13.5 days, as estimated just before approval reversed and started back up on May 15. I hasten to add that we lack enough data to be at all confident as to what the current rate of decline actually is. One point per 16 days is merely the best guess given current data. It might be less or more and will certainly change as new data come in.

So granted approval is now clearly going down, is the Newsweek poll telling us that the drop is of historic rapidity and that new polls will also show similarly dramatic drops, or is Newsweek's poll a statistical outlier-- getting the direction right but seriously overstating the magnitude of decline?

Based on all polling since 2002, the Newsweek result is clearly a statistical outlier. It is well below the 90% confidence interval in the figure below and is among the larger negative outliers of the past four years. The figure plots the residuals, the deviation from the trend estimate, for each poll taken since January 1, 2002. Orange points are polls that fall outside the 90% confidence interval, indicated by the low and high horizontal lines. The mean of all residuals is zero, the middle horizontal line. Newsweek polls are in red for easy identification.

Newsweek has a good polling track record, producing only one previous outlier in 70 polls. Here "outlier" is any poll outside the 90% confidence interval. By definition, we expect 10% of cases to fall outside that range. In fact, Newsweek has now produced two out of 71 polls since 2002 that are outside that 90% CI, a 2.8% rate. This latest poll, however, is clearly well beyond the lower limit of the interval.

Two recent polls have also fallen outside, but above, the 90% CI. Both of these were completed prior to the revelations about Representative Foley's IM messages to House pages, though after the now estimated peak of approval on 9/20.

Even if we focus on the four polls completed (at least partially) since the Foley Folly began, we see that all four are well below the trend estimate, but that the Newsweek poll is substantially below even these polls.

The conclusion is that the Newsweek poll is implausibly low, given the other data we have seen so far. A possible (but statistically less likely) alternative is that approval is falling very rapidly so that the unusually low Newsweek result reflects a much sharper rate of decline than the 1% per 16 days that I currently estimate. Such a rate of decline would be much higher than any yet seen in the Bush administration. I find this quite unlikely, but the data will answer this one way or another within a couple of weeks. For now, I'd bet the approval trend will fall another half point by the end of next week. If it falls much more than that, the Newsweek poll will look like a harbinger rather than a statistical fluke.

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