Manchester Bombing

Another tragedy in the long running war of terror vs civil society, apparently an attack claimed by ISIS.

From the Telegraph:

Monday, May 22, 2017, 10.30pm: Ariana Grande's concert ends. After the show's scheduled finish, thousands of fans begin to file out of the arena's four exits.

A "huge bomb-like bang" is heard at the arena. Witnesses describe being knocked from their feet by an explosion and seeing dozens of injured, possibly dead, people including children lying on the floor. Others describe panic as concert-goers run for exits.

By this time, reports say 22 have died, and 59 are injured. Police have arrested 4 people who may have been part of the planning and execution. The bomber killed himself in the act of murdering so many others.

Specific Hypothesis and Results

The GCP event was set for 6 hours beginning at 10:30 pm local time. This corresponds to 21:30 UTC plus 6 hours. The result is Chisquare 21540 on 21600 df, for p = 0.613 and Z = -0.286.

Interpretation

The following graph is a visual display of the statistical result. It shows the second-by-second accumulation of small deviations of the data from what’s expected. Our prediction is that deviations will tend to be positive, and if this is so, the jagged line will tend to go upward. If the endpoint is positive, this is evidence for the general hypothesis and adds to the bottom line. If the endpoint is outside the smooth curve showing 0.05 probability, the deviation is nominally significant. If the trend of the cumulative deviation is downward, this is evidence against the hypothesis, and is subtracted from the bottom line. For more detail on how to interpret the results, see The Science and related pages, as well as the standard caveat below.

Standard caveat

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.