Article: Authors admit errors in study on bike helmets and head injuries

[ozbob]

From the Brisbanetimes click here!

Authors admit errors in study on bike helmets and head injuries

Authors admit errors in study on bike helmets and head injuries
Matthew Moore
December 30, 2010

TWO academics have apologised for publishing a study which said compulsory helmet laws for cyclists did not reduce head injuries after a critic identified errors in their research.

Associate Professor Chris Rissel, from the University of Sydney's school of public health, and Alex Voukelatos conceded they had made arithmetic errors in their peer-reviewed article, published in the August issue of The Journal of the Australasian College of Road Safety.

In the latest issue of the journal, the authors concede a number of mistakes identified by a medical epidemiologist, Dr Tim Churches, who challenged their finding that laws introduced across Australia in 1991 were not responsible for a fall in head injuries.

''Churches is quite correct in writing that the paper ... has serious arithmetic and data plotting errors,'' they wrote in the latest issue.

''We sincerely apologise for these unintentional errors and any confusion that this may generate.''

Dr Rissel said the mistakes resulted from ''transcription errors'' from repeated computer runs to generate the data used in the study, while ''data plotting errors'' in the graph were a result of re-scaling of the graph without adequate checking of the positioning of the added figures.

When advised of the mistakes, he said he had obtained additional data from Western Australia and Victoria which confirmed the original findings that general improvements in road safety before the compulsory helmet laws were behind the fall in head injuries among cyclists.

''Our original conclusion is quite reasonable,'' he said.

He is hoping to publish his additional research in the same journal early next year.

In his original study, Dr Rissel analysed the ratio of head injuries to arm injuries among cyclists admitted to hospital between 1988 and 2008. He assumed the ratio would not change unless helmet use reduced head injury rates compared with arm injury rates.

Dr Churches said no such conclusions could be drawn from the study because of the errors.

While Dr Churches said he would wait to see what the additional research might say, he believed compulsory wearing of helmets had helped to reduce head injury rates.

''It is now clear that the Voukelatos and Rissel study provides no new impetus for the Australian cycling helmet laws to be repealed,'' he said.

''There's nothing in that data which suggests the legislation did not have an impact.''

[johnnigh]

So, the errors don't actually make any difference to the conclusions, as the article makes clear (that at least is true, I've read the various articles in the learned journal in which they were published. However, the journalists have chosen to give a simplistic and misleading headline that suggests that Dr Churches has revealed something seriously wrong with the original paper - which is not the case. Churches has a history of histrionics about helmets. His conscientiously held view that a bicycle is so dangerous to the head that adults cannot be trusted to make informed decisions (whereas he doesn't appear to support compulsory sunscreen and hats for all persons who venture outside, despite the skin cancer killing many times the number of bicycle people killed by cars) is not a view held by everybody. The health benefits of helmets would be far greater if applied to pedestrians and car drivers and passengers. But the good Dr doesn't seem to support this either :conf!