The EarthDance event is a global electronic music party organised each year as a peace meditation -- through dance. It has been happening since 1997, usually in October, though in 2004 the date is September 19. Typically there are 100,000 people dancing in 100 cities. All the participants connect in a synchronized "Prayer for peace", played simultaneously at one point in time in all dance locations.
The time specification for the prayer was a little confusing this year. The main website said Midnight GMT, but in other places the published time was for Midnight in London (23:00 GMT), which corresponds to 19:00 in New York and 16:00 in California. We took the latter as the intended time, and the formal event was specified as in 2002, from 22:50 to 23:15 GMT, surrounding the moment set for the synchronized prayer for peace.
The following graph shows the results, which have a strong and consistent downward trend. The Chisquare is 1414.245 on 1500 df, corresponding to Z = -1.584 and p = 0.943.
There were other organized events on the 19th, for example 5 hours earlier in the day. There were also some instructions for a detailed pattern of attention in 5 minute segments. I believe this was promoted only for a small subset of people, but it is possible to gauge the effect by an informal look at the graph. It shows no discernable corresponding pattern of changes in slope.
Finally, it is interesting to note that the full GMT day of the 18th has about the same slope as the test segment shown in the graph.