S&P Downgrade plus Helicopter Crash
The 5th of August was not a great day for the US. We were braced for a possible downgrade of the US Government bond rating from its AAA level, and late on Friday (I haven't been able to find the actual time) Standard and Poor announced a downgrade to AA+, the first time in history this happened to the US.
Then, early on the 6th we heard about a helicopter crash in Afghanistan during the night (described as late Friday), with 31 special forces killed, and 7 or 8 Afghans, and all indications were that the Taliban had brought it down with a rocket grenade. The news further indicated that most of the Americans were from the Navy Seal Team 6 that had famously killed Osama Bin Laden.
I originally set this event to cover the approximate time of the helicopter crash plus 6 hours for the news to spread, but then recognized that there was a coincidence with the news of the US credit rating downgrade and the immediate plunge of stock market futures. I decided to name the event for both of these somewhat shocking news items, and to provide some description to give GCP readers a flavor of the complexity we deal with in identifying events for analysis. In fact, such overlaps of potential GCP events are common, and we have to depend on precise timing and limited duration of defined events to help disentangle them.
In this case, especially because we don't have precise times for either event, the outcome is ambiguous. There is no significant trend, and the test statistic is modestly negative. The result is Chisquare 21483.105 on 21600 df for p = 0.712 and Z = -0.560.
It is important to keep in mind that we have only a tiny statistical effect, so that it is always hard to distinguish signal from noise. This means that every "success" might be largely driven by chance, and every "null" might include a real signal overwhelmed by noise. In the long run, a real effect can be identified only by patiently accumulating replications of similar analyses.