Did the long-timescale character of the GCP data change after 9/11?.
Vertical bar marks Sept. 11, 2001. [a constant scale factor has been applied to plotted values]
The plot shows the cumulative deviation of the daily values of the network variance from Oct 1, 1998 to Sept. 8, 2004.
There are 2166 plotted daily values. [there is no GCP data for the period Aug 5-8, 2002]

Is there a change in network behavior associated with major world events related to terrorism and terror politics?
Polls that ask the question: Do you approve or disapprove of the way the president is handling his job? probe a general sense of political and societal well-being.
Does the network variance grow when there are strong, persistent feelings of unity, rally and common purpose?
Does the network variance decrease when there are strong, persistent polarizing forces?

Figure caption: Red trace: US Presidential approval ratings from 6  US polling sources (AP, Harris, Gallup, ABC, Pew, NBC). Blue trace: cumulative deviation of GCP network variance (variance of network mean at one-second resolution). Vertical bars mark major events: Bush Inauguration, shaded region I: Terrorist attack and Afghan campaign (9/11 attacks , Sept 11, 2001 to announcement of Taliban defeat, Dec 16, 2001) (Note: Afghan bombing began Oct 07 2001), shaded region II: Iraq campaign (official announcement of bombing , March 19, 2003 to announcement of end of "major combat operations", May 1, 2003), capture of Saddam Hussein (Dec 13, 2003), Madrid terrorist bombings (March 11, 2004), Bush re-election.

The poll results are for 556 separate polls from Aug 9, 1998 to Dec 15, 2004. Poll dates are take to be the closing day of the polling period [most polls are conducted over 3-4 days]. Values are averaged when more than one poll closes on the same day. There are 506 data points representing 506 unique polling dates.

Some discussion of interpretations may be of interest, but it is necessary to keep in mind that all interpretation at this point is post facto, and not useable as scientific evidence.

Same as above, with 3-pt smoothing of poll results.

Same as above, with 8-pt smoothing of poll results and 20-pt smoothing of the netwok variance.

Below: Point-to-point increments. This is the network variance, without performing a cumulative sum (blue) and the change in poll rating for consecutive polls (red). The values have been re-scaled for visual  comparison.

A view of the network variance cumdev and poll plots when both are normalized to unit variance. [normalizations calculated from the real point-to-point values]