Are helmet laws suppressing cycling?

If maps were based on time not distance, this is how big (and small) the Netherlands would look

A new Australian study has thrown more fuel on the fiery debate about whether or not bicycle helmets should continue to be mandatory. Its headline claim is 23% of Sydneysiders say they would cycle more if they weren’t obliged by law to wear a helmet.

This isn’t merely saying that some people would prefer to cycle without a helmet – it’s claiming the law actually suppresses cycling.

I lean toward the school of thought that says mandatory helmets probably do more harm socially than good, but as I’ve said before, it’s not the sort of issue that I would want to die in a ditch over. However if there were reliable evidence that compulsory helmets actually restrain cycling, that would require a rethink.

The research was undertaken by Professor Chris Rissell and his colleague, Li Ming Wen. It is published in the latest edition of the Health Promotion Journal of Australia, under the snappy title, The possible effect on frequency of cycling if mandatory bicycle helmet legislation was repealed in Sydney, Australia: a cross sectional survey.

It’s a brief and easy to read article but a summary by Professor Rissell was published on The Conversation last week, Make helmets optional to double the number of cyclists in Australia. Professor Rissell is a self-confessed cycling advocate and firmly in the activist “repeal” camp on helmets.

He and his colleague surveyed 600 Sydney residents aged 16 years and over. They found one fifth of respondents “said they would cycle more if they did not have to wear a helmet, particularly occasional cyclists”. They conclude that:

While a hypothetical situation, if only half of the 22.6% of respondents who said they would cycle more if they did not have to wear a helmet did ride more, Sydney targets for increasing cycling would be achieved by repealing mandatory bicycle helmet legislation. A significant proportion of the population would continue to wear helmets even if they were not required to do so.

Regrettably, I don’t think this study adds anything to our knowledge of whether Sydneysiders would ride more if helmets weren’t compulsory. They might, but then again they might not. The trouble is the survey relies on a hypothetical situation: “Would you cycle more often if you didn’t have to wear a helmet? Yes or No?”.

Hypothetical survey questions are notoriously unreliable. I’m not picking on the anti-mandatory helmet brigade here – I also took Metlink to task earlier this year for trying to make grandiose predictions about future public transport patronage based on a similarly unreliable methodology.

It’s standard practice to avoid hypothetical questions in surveys. Consider this advice from The World Bank publication, The Power of Survey Design:

Hypothetical questions, especially, should be avoided. People cannot reliably forecast their future behaviour in a hypothetical scenario. Thus, the questionnaire design should make careful use of this style of question.

Hypothetical questions are especially problematic when respondents are asked to predict an activity they’ve had little experience of. The Canada Business Network advises questionnaire designers, if possible, to “avoid hypothetical or future intentions questions:

Hypothetical questions force the respondent to provide an answer to something he or she may never have thought about and, therefore, the respondent may not be able to provide an accurate response.

The authors should’ve been alerted that all might not be right when they found 40% of those who say they’d cycle more if helmets weren’t compulsory, also say they support mandatory helmet legislation. Yes, there’re scenarios where it’s conceivable someone could hold both views simultaneously, but 40%?! Read the rest of this entry »

Does being the most liveable city in the world mean anything?

EIU's ten "most liveable" cities in the world (scores out of 100)

The good thing about ‘winning’ the World’s Most Liveable City gong is that it might help market Melbourne to overseas tourists, students, investors and maybe even buyers of our services. Unlike the Grand Prix, it costs us nothing. And while it won’t stop some Melburnians from pissing in trains (like this guy in case you missed him in yesterday’s post), it might give many others greater pride in their city. The thousands of Melburnians who travel overseas for business or pleasure each year can now be ambassadors for their city with this neat and handy marketing tool.

But of course league tables like The Economist Intelligence Unit’s (EIU) annual Liveability Survey are all bunkum and sensible people shouldn’t be sucked in. The EIU’s Survey purportedly provides an objective ranking of world cities based on 58 variables measuring dimensions like political stability, health care, environment, culture, education and infrastructure. However, as I’ve explained before (here, here and here), there are a number of reasons why liveability league tables are best left to the marketeers.

The EIU’s Survey is designed primarily to assist companies with formulating appropriate living allowances for staff posted to overseas cities. These people are transitory and well-heeled – they don’t experience the city like the average permanent resident. They usually rent somewhere convenient and salubrious, so they won’t care too much about high housing prices and inadequacies in outer suburban public transport.

There are also difficult methodological problems involved in arriving at a single summary ranking of a city’s “liveability”. These sorts of surveys typically have lots of variables – some are easy to measure, others are very subjective. The analysts often make the convenient but unrealistic assumption that they’re all of equal value (weight). Not all of them can be ‘added’ together in any meaningful sense, yet they have to be to arrive at a simple league table.

The differences between top cities in these sorts of surveys are in any event miniscule and hence of little consequence. For example, the top five ranked cities in the EIU’s survey all scored 97 points out of 100 (see exhibit) – this would be swamped by the margin of error in the estimates. The EIU acknowledges that “some 63 cities (down to Santiago in Chile) are considered to be in the very top tier of liveability, where few problems are encountered…. Melbourne in first place and Santiago in 63rd place (can) both lay claim to being on an equal footing in terms of presenting few, if any, challenges to residents’ lifestyles”.

Defining “liveability” is itself a difficult challenge (I’ve discussed this before in the context of the ‘Sydney vs Melbourne’ debate – see here and here). The EIU finds the concept so slippery it comes up with this tautology: “The concept of liveability is simple: it assesses which locations around the world provide the best or the worst living conditions”. Arriving at a consensus definition is extremely hard because it depends on a number of factors, like the characteristics of the observer – for example, their ethnicity, their income, their stage in the life cycle and so on. The vibrant centre of Melbourne might add nothing to the city’s liveability for someone who’s elderly, or on a low income, or a member of a cultural group that is under-represented in the city.

It’s not surprising the EIU’s top ten cities seem to be all of a one. They’re all medium sized cities (no megalopolises here), they’re practically all low to middling density, they’re all in first world countries and, with the possible exception of Sydney, they all have cool to cold climates. What seems obvious is that the ranking is shaped much more by the characteristics of the host country than anything else. Factors like political stability, health and education – which loom large in the selection calculus – are pretty much the same whether you’re in Melbourne, Sydney, Perth, Adelaide or Auckland.

I would be more inclined to focus on the attractiveness of a city and measure how sought after it is (perhaps by looking at the difference between wages and housing costs). It’s instructive, I think, that few of the cities in the EIU’s top ten are the sorts of places young people around the world seem to aspire to live in. Let’s be realistic, Australian cities don’t have quite the drawing power of places like London, New York, Los Angeles, San Francisco and Paris.

The slightly different methodology used by the rival Mercer Quality of Living Survey ranks Sydney 10th and Melbourne 18th. This is a big drop in ranking for Melbourne compared to the EIU Survey, but again the difference in ranking is far larger than the difference in absolute scores, which is small. Read the rest of this entry »