Tuesday, May 22, 2007
Pres08: Short-term Giuliani-McCain Trends
I usually focus on the full set of polls available for an analysis. But sometimes it pays to zoom in on only some recent trends. In the case of the Republican presidential nomination battle, zooming in clarifies things a bit.
I've written about this, and compared my more sensitive estimator ("Ready Red") with my more conservative one ("Old Blue") in several places (here, here, and here.)
While I usually prefer the more conservative estimator because it is harder to fool it with a few polls, in this case it is clear that the Giuliani trend has taken a downturn since March. The evidence for a McCain upturn is much less compelling, but the red estimator thinks it sees a little bit of one.
In the plot above, it is clear that the sensitive red estimator follows the data rather well since early November when presidential nomination polls became frequent. The Giuliani trend clearly illustrates his substantial run-up but also his subsequent decline. The trend estimator now stands a point below where Giuliani began in November.
McCain, on the other hand, was in decline from December until about April 1. Since then he appears to have gained a couple of points.
This means that a substantial gap that Giuliani opened on McCain in the first quarter of the year has now largely disappeared. Giuliani has been ahead of McCain in the vast majority of polls, including 54 of the 56 polls taken since November 1 (see here as well). But that gap is narrowing.