Trying to deny that the helmet law reduces cycling

Abstract

Cycling was rising strongly in Australia before the helmet law, by 10% per year.  This uptrend was replaced by a sharp decline of 30 to 40% after the helmet law. 

A study has misrepresented a bicycle rally passing through a counting site as a revival in cycling numbers, obfuscating the decline in cycling after the helmet law.

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Bicycle travel in Australia was increasing by 10% a year from 1986 to 1989, before the introduction of the helmet law. This uptrend was replaced by a sharp drop after the helmet law, showing a decline of 30 to 40% according to several independent surveys. An independent assessment estimates that cycling levels were 50% below previous trend by 1996.

The police harassing cyclists not only deters those cyclists, but also many others who do not want to risk harassment. Those who have given up cycling because of this are not easy to see. The thousands of cyclists fined every year for riding without a helmet are only the tip of the iceberg.

 

The Monash University Accident Research Centre (MUARC) has published many studies defending government policy, funded by the Victorian government. In the early 1990’s, MUARC conducted several studies, like this one, claiming that the helmet law had reduced head injuries. They ignored that when the lower number of cyclists, and safety benefits from pedestrians at the same time period, are taken into account, the risk of head injuries for cyclists actually increased. It is odd that such a fundamental mistake as failing to adjust for the number of cyclists favors the legislation while the government funds the “research”.

MUARC also conducted this study that appears to indicate that adult cycling recovered two years after the helmet law in Melbourne. With government funded studies, the full study must be read carefully to figure out what is really going on.

According to the study, child cycling did not recover, dropping by more than 30%.

MUARC_count_child_cyclists

The helmet law resulted in a sharp drop child cycling.

Yet strangely, it appears that adult cycling recovered in 1992.

MUARC_count_adult_cyclists

Why would adult cycling recover but not child cycling?

A bicycle rally passed through one of the survey counting site in 1992, but not in 1991. At that site, there were 72 cyclists counted in 1991, and 451 cyclists in 1992, more than 6 times more. That is 30% of all cyclists counted on 1 out of 105 counting sites. Excluding that site, there were 27% fewer cyclists in 1992 than in 1990, similar to 1991, like what was observed for child cyclists.

The whole point about those comparisons is to keep everything else the same – same sites, same observation periods, same time of year, so that you are measuring the effect of the intervention, not random noise. The study authors knew about the bicycle rally passing through one of their counting site in 1992, but not in 1991. Yet they included it in the study, claiming that:

“Another explanation for some of the increase in bicyclist numbers in 1992 is related to the fact that there appears to have been a bicycle rally passing through one of the sites …
From a statistical point of view, however, an occurrence such as this is a true observation, well within the bounds of “normal” behaviour for that time period, and cannot be excluded from the analysis”

The 1992 overall adult cycling count was similar to 1991. One site where a bicycle rally passed through in 1992 but not in 1991 showed a 6 TIMES increase. How can it sincerely be argued that this site is within “normal behavior”? It clearly distorts the results. Yet the authors chose to include it, and thus to publish a misleading result misrepresenting a bicycle rally passing through a counting site as a revival in cycling numbers. Such unethical behavior is not unusual among government funded “studies” defending government policy.

 

Despite being exposed as misleading, this “study” is still used to claim that cycling recovered within two years. Some go even further. A recent “study” commissioned by the Queensland government claims that

 “In Melbourne adult cyclist numbers doubled after the helmet legislation was introduced”.

, quoting the deceptive study mentioned above. How they arrived at this conclusion is a mystery. This seems like lies building upon lies, in a creepy fashion.

However it may be not be the study authors to blame. This “study” was edited several times by bureaucrats from the Queensland department of transport, in favor of the legislation. This leaves a dreadful feeling of living in an Orwellian world, where bureaucrats try to rewrite history that is convenient to them, obfuscating any trace of their past mistakes.

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One Response to “Trying to deny that the helmet law reduces cycling”

  1. Douglas Yardley says:

    Recent studies cited in “City Cycling” ed. by J.Pucher and R.Buehler cast doubt on the value of helmets. I have personally cycled 184,000 km since 1996 and have had only one minor accident. I started using a helmet in 1981 but frankly I think a rear-view mirror has greater safety value.

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