OCBCOCBC
      STATISTICAL ANALYSIS or SOCIAL ENGINEERING?

      A Critical Review of a Statistics Canada
      "Factors Associated with Bicycle Helmet Use"
      by Avery Burdett


      BACKGROUND

      Statistics Canada, a federal government department has published an article titled "Factors Associated with Bicycle Helmet Use" in the Autumn 1997 edition of Health Reports (vol. 9 no. 2). This article has as its stated objective "to examine characteristics associated with the use of bicycle helmets by children and adults." and uses data from the 1994/95 National Population Health Survey to determine the use of bicycles and bicycle helmet use. However, based on a reading of the discussion of results of the statistical analysis and on a critical examination of sources of information cited, it appears the authors had much more in mind than to merely look at bicycle helmet usage. The last section of the report entitled "Implications" reveals the real intent of the authors, Statistics Canada analyst Wayne J. Millar, a self-professed helmet enthusiast, and Ivan B. Pless of the Montreal Children's Hospital. Buried in this section is a trojan horse plea for universal mandatory bicycle helmet legislation. Although an area of public policy outside the scope of Statistics Canada's mandate, this might have been slightly more palatable to experienced and knowledgable cyclists had the discussion been objective and the sources of research current and credible, but as the following review demonstrates, they are anything but.

      EXTRAORDINARY STATEMENTS AND CLAIMS

      The Efficacy of Bicycle Helmets

      The Statistics Canada article claims several studies have demonstrated that head injuries can be prevented through the use of helmet (p31). But several other studies have concluded the opposite also. No reduction in the rate of head injuries, serious head injuries or deaths in jurisdictions (New Zealand, Australia and US) where helmet use has been heavily promoted and mandated. Why were these other sources ignored?

      Associating General Injuries with Helmet Purchase

      The article states that since parents from the lowest income groups were less likely to perceive injuries as the leading cause of death among children, they may have been less likely to consider a bicycle helmet a necessary purchase (p34).

      This statement is difficult to fathom since it refers not to cycling injuries which result in a small percentage of accidental deaths of children but to deaths suffered by children in all types of accidents. The association with bicycle helmets lacks an obvious cause and effect.

      Misleading Use of Statistics

      The article cites a Kingston, Ontario study where 8% of head injuries to those under the age of 20 involve cycling (p36). Since the authors don't say, this begs the question what proportion of these were wearing helmets? By 1996 the year of the study, helmet use had increased significantly as a result of the helmet law in Ontario (applying to those under 18). In about half of the fatalities in Ottawa over the past three years, the victims were wearing helmets. If helmeted children had been overrepresented among the injured what would that say about the efficacy of a bicycle helmet? It raises contextual questions too. Given the amount of time children spend on bicycles, 8% of child head injuries doesn't seem excessive. What activities were the victims involved in which make up the other 92%? What percentage was from motor vehicle use? In 1993 according to the Ministry of Transportation of Ontario's Road Safety Annual Report, virtually all road deaths of those under 20 involved motor vehicles. There was no involvement of a cyclist in 93% of them. Motor vehicle use accounted for over 78%, and 15% were pedestrians. This shows that those under 20 year of age are eleven times more likely to be killed inside a car and twice as likely to get killed while walking. Since the majority of these deaths involve head injuries, one wonders why cyclists are singled out for special treatment. By focussing on the effect of accidents involving a small minority of road users, the authors bypass important issues - the cause of accidents and their prevention among all road users.

      Citing a 1983 Florida study, the report states "research suggests 9 out of 10 fatalities involve injuries to neck and head" (p37). Under the caption "Cycling Deaths" it states "almost two-thirds of fatalities involve head injuries". The authors quote these figures without adjusting them to remove numbers of fatalities where a helmet would have played no role. For example, the first figure includes neck injuries, injuries which cannot be prevented by a helmet. But the report does not say how many out of 9 were neck injuries. Was it 8 or was it 1? Also the use of the word "involve" implies that head injuries were not the sole factor or cause of all fatalities. Furthermore, head injuries include injuries to ears, face, jaw and other parts which are not protected by a helmet. The only relevant figure in this discussion is the number of fatalities among bareheaded cyclists whose sole cause of death was a head injury for which a helmet purports to offer protection. Clearly both the 9 out of 10 and the two thirds figures are misleading, yet the authors made no effort to adjust it or caution readers on its interpretation. One must ask why? Could it be that the authors need to overstate the problem?

      Another example of selective use of figures of doubtful relevancy is the claim "Helmets reduce the risk of serious head injuries by up to 85%." This is taken from Thompson, R., Rivara, F., & Thompson, D., A Case Control Study of Effectiveness of Bicycle Safety Helmets, New England Journal of Medicine, 320: 1361-67, 1989 which claimed helmets reduce the risk of head injuries, not serious head injuries as claimed by Millar and Pless, by 85%. This report is a study of cyclists received at emergency rooms at Seattle area hospitals. It has been widely distributed because it claimed the highest effectiveness rate of any helmet study. Other studies have suggested much lower risk reduction (as low as zero). Concern has been expressed by experts over Thompson et al's selection of cases and controls, and methods of adjusting for age group disparities. Also, the nature of injuries typically received at the ER are minor and not representative of the serious head injuries which are popularly, but wrongly, perceived to be prevented by helmets. There have been studies showing no helmet effect in severe impacts. "Serious and unsurvivable head injuries do not differ in relative frequency between helmet wearers and bareheaded cyclists (McDermott, FT et al, Effectiveness of Bicyclist Helmets: a study of 1710 casualties, 1993, Journal of Trauma, vol 11:6 pp 834-45). The authors of this study looked at the Thompson et al data and concluded the rate of effectiveness to be much lower. Despite the abundance of contrary evidence, Statistics Canada adopted the highest risk reduction claim available, and then compounded the distortion by misquoting the article to make the claimed efficacy of bicycle helmets even greater. Was this just sloppy work or a deliberate attempt to mislead?

      The authors take the 85% figure from Thompson et al and improperly link it to another figure in the following quote "... yet just 4% of persons involved in fatal bicycle-related accidents in Ontario between 1986 and 1991 were wearing helmets". The Thompson et al study was not a study of fatalities but, as mentioned above, injuries received for emergency room treatment. So they discuss helmets and fatalities but cite an analysis of mostly minor injuries. In addition, context would have been helpful to put the figure in perspective since helmet use was very rare in the 1980's. If the helmet wearing rate among the population was less than 4%, then a professional statistician would have asked why helmeted cyclists were overrepresented in fatalities. In NSW, Australia (1992) 82.4% of cyclists killed were wearing helmets. The helmet wearing rate at the time was 81.7%. For the period 1992 to 1994 the rate of helmet wearing was matched by the rate of helmet wearing among fatality injured cyclists (data from Road Transport Authority, NSW). In a total of 11 years of child helmet legislation among 8 states in the US, no statistically significant drop in fatalities has been recorded (data from US National Highway Traffic Safety Authority). Why didn't the authors examine such data? These results were well known among cycling groups who oppose helmet legislation, and freely available over the Internet.

      But Figures Show Kids Need Skills

      Had the authors done a thorough analysis of their own data, they might have obtained an insight into the real issue. P37 shows percentages child cyclist deaths among the population between 1980 and 1994, a period of no or low helmet use. Fatalities represented 4% of children under 10 years, 10% of those 10 to 14 years, and 2% of those 15 to 19 years. The large differences between age groups should have been scrutinized. Fatalities bulge in the middle (10 - 14) age group. The most likely explanation is that the skills of cyclists improve with age with the very youngest cyclists receiving close parental supervision. Studies show that the more persons ride bicycles, the better their skills get and the fewer accidents they are involved in. The decline in the rate of deaths among older children suggests skills, and therefore educational approaches, are more relevant in strategies to reduce cyclist fatalities.

      The Selling of Helmet Legislation

      The last section is where the real motives behind Statistics Canada article can be found. It says "Although one study suggests this [reduction in head injuries] is partly attributable to a reduced number of riders, the net effect [of helmet legislation] is clearly beneficial. For example, in Victoria [Australia], after legislation made bicycle helmets mandatory there was a marked increase in the rates of use between 70% and 90% within a year and a substantial decline in head injuries and mortality." (P38).

      This is a carefully crafted statement which masks the truth. The rate, or percentage, of cyclists wearing helmets can increase while at the same time cycling declines. In Australia, that appears to have happened. There is an abundant amount of evidence indicating declines in the numbers of Australians cycling, as is conceded by the authors. Regardless of helmet usage, a decline in head injuries and mortality was to be expected if participation in cycling declined. But no explanation of this is offered by the authors even though it would be fundamental in carrying out a statistical analysis. Robinson, D. L., Head Injuries & Bicycle Helmet Laws, Accident Analysis Prevention, Vol 28, pp 463-475, 1996, a study of Australian road victim accidents, states "the most remarkable aspect of the data both from Victoria and New South Wales is that the decrease in numbers of cyclists was at least as large as the decrease in numbers of head injuries and larger than the total decrease in injuries. This suggests cyclists are now worse off than before the law." From the same source, it states that following the helmet law in New South Wales, the cyclist proportion of deaths and serious injuries among child road users actually increased. In the two years prior to the law in New South Wales, 19 (1989) and 20 (1990) cycling fatalities occurred. In 1994 following legislation 23 cyclist fatalities occurred with a 76% helmet use rate and a 30% to 40% decline in cycling. Why didn't the authors track down these facts? A thorough and unbiased search of available research would have uncovered them.

      The Statistics Canada report doesn't just limit its efforts to analyses of data. It moves into another field of competence - behavioural science - by stating "However, current research suggests that education alone is not sufficient to reach and maintain high levels of helmet use and that legislation is needed.", "However, making laws applicable to the entire population would reinforce their importance, and peer approval might be reduced", and "More important from a public health perspective, ..... bicycle-associated injuries creates a health burden regardless of age". All three opinions are unsubstantiated. All three are highly questionable, And all three trespass into policy areas where Statistics Canada has no business.

      CONCLUSIONS

      So what does this tell us?

      1. A report which has Statistics Canada stamped on it immediately is accorded credibility which will tend to limit rational discussion. But had the authors involved experts in the field of cycling - professionals and experienced club cyclists - different conclusions might have been forthcoming.

      2. There is a plethora of evidence from countries with mass helmet use that helmets have little effect on the rate of head injury among the population. Furthermore, cycling is a life extending activity. By exaggerating the problem of cycling accidents, cycling is falsely made to appear dangerous. This has the effect of discouraging some from cycling, as happened in Australia. Considering the enormous cost to Canada of heart disease - it causes premature death of 1,000 Canadians for every premature death of a cyclist - we can ill afford to implement a strategy which negatively impacts the fitness of Canadians.

      3. Even in provinces with helmet laws, teenagers are reluctant to wear helmets. When they do, as many as a half are improperly fitted. Police don't have the desire or resources to chase after kids, so children learn very quickly to ignore the law. This sends the wrong message.

      4. It has been shown that virtually all road deaths involve a motor vehicle and young folks are 13 times more likely to be killed as car users or pedestrians than they are as cyclists. An approach which treats the symptoms not the cause, benefits no one. It would be far more useful to parents if they were made aware of the much greater danger motor vehicles pose to their children while the kids are walking or passengers in a car. By forcing a small segment of road users to be responsible for protecting themselves amounts to victim blaming. This is not only a disservice to young Canadians and their parents but also a grave injustice.

      5. Statistics Canada is a government agency whose expertise is in the field of gathering, assembling, and analysis of data. It is improper to take public policy positions or to endorse predetermined biases, regardless of how politically correct they appear. Sometimes it is necessary to present factual data which are unpopular or politically unwelcome. Even so, based on the contents of this report, it is difficult to find any objectivity. It looks as though there has been a deliberate attempt to distort facts. If that is not the case, then the report represents an extremely sloppy piece of work.

      6. Individual officers of the agency should not be pursuing subjects because of personal interest (which it was in this case). It amounts to creating "make work" projects, a pastime Canadian taxpayers can ill afford.

      7. Most important, Statistics Canada has no mandate to develop social policy, yet this document explicitly calls for the adoption of policy positions in the areas of health, law and education. Worse still, the policies, if implemented, infringe on the fundamental rights and freedoms of millions of Canadians.

      Statistics Canada owes Canadians an explanation.


February 1998
Return to: Home