Hadj Stoning Stampede 2015

(CNN)A stampede during one of the last rituals of the Hajj season -- the annual Islamic pilgrimage to Mecca -- has killed more than 700 people and injured close to 900 others in Saudi Arabia.

The stampede occurred Thursday morning during the ritual known as "stoning the devil" in the tent city of Mina, about two miles from Mecca, Islam's holiest city. Pilgrims were walking toward the largest of the pillars when there was a sudden surge in the crowd about 9 a.m., causing a large number of people to fall, the Saudi Press Agency said, citing civil defense officials.

Hundreds have been killed in past years during the same ceremony, and it comes only 13 days after a crane collapse killed more than 100 people at another major Islamic holy site, the Grand Mosque in Mecca. This is a strict replication, as the GCP specified a formal event in 2006 when the same kind of stampede occurred during the stoning ritual.

Civil defense authorities said the latest death toll is 717, with 863 people injured, but the numbers have been climbing steadily. Officials deployed 4,000 workers, along with 220 ambulances and other vehicles, to Mina in response to the disaster.

In the ritual, crowds of pilgrims throw stones at three pillars in a re-enactment of when the Prophet Abraham stoned the devil and rejected his temptations, according to Muslim traditions.

Specific Hypothesis and Results

The GCP event was set as a replication of the 2004 Hadj, for four hours beginning one hour before the surge and stampede. The UTC times are 05:00 to 09:00. The figure below shows the timing of the stampede.

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.

We did a second, exploratory and informal analysis to look at the context for this tragic event. The Hadj is actually a spiritual pilgrimage, with many millions focused on their desire to participate in addition to more than 2 million Muslims from around the world who are attending the annual Hajj pilgrimage this year.

Known as the fifth pillar of Islam, the Hajj is an obligation upon every Muslim who has the financial means and the physical ability to perform it. For most, it is the spiritual climax of their lives, with many saving for decades to make the journey. The figure shows a strong deviation in the direction we predict for the first several hours of the day, but after the stampede, the data show no substantial trends for the rest of the day.

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.