Newsweek's poll, taken 5/11-12/06, finds approval of President Bush at 35%, with disapproval at 59%. The 35% reading is a bit above recent CBS/NYT, Gallup and Harris figures that are all at or below 31%, but the Newsweek result is in line with Cook, CNN and AP polls of recent vintage. In terms of my model's estimated trend, Newsweek is within the usual margin of error for the trend. The trend stands at 32.3% (including the Newsweek poll). My 90% confidence interval around the trend is +/- 3.7%, so 35% is confortably within that range.
It is interesting to look at the history of Newsweek polls since January 2005. Newsweek does relatively little polling, but they have been consistently below the trend for all polls. The estimated "house effect" for Newsweek is -2.18% compared to the average across all polls. As the light blue line in the figure shows, that negative house effect has been quite consistent. Until this latest poll.
The take home point is that even a consistent house effect remains subject to random variation in individual polls. That Newsweek is above trend this time doesn't imply that it will stay there. If the past is a guide, we should expect the next Newsweek poll to again be somewhat below trend. And if that happens, we shouldn't confuse a large downward change with all being due to "true change". Some of it is just replacing one (postive) random number with another (having expectation -2.18.)
(Apologies for the tardy post-- much family activity this weekend.)
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