Restaurant Siege, Sydney Australia
Standard analysis
Two people died, along with an Islamist gunman, after commandos stormed a cafe in Sydney, Australia, to bring to an end a 16-hour siege. Local media have named those who died as Lindt cafe manager Tori Johnson, 34 and lawyer Katrina Dawson, 38. Four people were injured, including a policeman hit by shotgun pellets. Central Sydney was put in lockdown as the gunman, identified as an Iranian refugee, seized dozens of hostages early on Monday.
Events unfolded in full view of the media:
09:45 Monday local time (22:45 GMT Sunday): Police are called out to the
Lindt Chocolat Cafe in Sydney's Martin Place, a busy plaza in the heart
of the city. Suggestions an armed robbery is under way are soon
discounted
10:09: Australian TV stations broadcast footage of hostages holding a
black Islamic banner up to the window. The gunman can also be seen,
wearing a bandana
12:30: As police flood the area, Prime Minister Tony Abbott goes on
national TV to promise a thorough police response to the "deeply
concerning incident"
16:00-17:00: Three men, then two women, sprint to safety from the cafe's
fire exit
18:30: Police confirm negotiations are under way with the gunman
02:20 Tuesday (15:20 GMT Monday): Several more hostages escape and
commandos storm the cafe
02:48: Police officially confirm end of siege. They later report the
deaths of three people, including the gunman
Specific hypothesis and results
The GCP event was set for an 18 hour period beginning somewhat before and ending a bit after the timeline above. (22:00 Dec 14 to 16:00 Dec 15 GMT). The result is Chisquare 64519 on 64800 df for p = 0.782 and Z = -0.779.
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 bottome 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.
