How many people will be at the Rugby World Cup’s Opening Night celebrations in Auckland?

Expect to hear a lot of big numbers thrown about during the Rugby World Cup – and not just about those on the field.

When Auckland hosts the Rugby World Cup Opening Night Celebrations this Friday, people will want to know how many turned up. The success of the event (and justification for the expenditure) will be measured in part by estimated crowd size.

Crowd estimation is often not at all scientific. During tonight’s ONE News bulletin, reporter Jack Tame estimated there were “five or ten thousand delirious Tongan fans”.

How are crowd estimate figures obtained and how reliable are they?

The authors of a new study published in Significance, the magazine of the Royal Statistical Society and the American Statistical Association claim that most crowd estimations are unreliable and that the public should view crowd estimation with scepticism:

“In the absence of any accurate estimation methods, the public are left with a view of the truth coloured by the beliefs of the people making the estimates,” claims Professor Paul Yip, of the University of Hong Kong, one of the authors of the study.

“It is important to rectify the myth of counting people. The public would be better served by estimates less open to political bias. Our study shows that crowd estimates with a margin of error of less than 10% can be achieved with the proposed method.”

Further reading:

• How many were there when it mattered?
• Feeding the Five Thousand – or was it Three?
• The Protest Numbers Game

Also of interest:

• Royal Wedding TV audience closer to 300m than 2bn