Editor—That the observation by Walker et al of more unsafe behaviour by the drivers of four wheel drive vehicles provides “strong support” for the risk compensation theory is unconvincing. This theory implies that because drivers feel intrinsically safer in bigger more robustly built vehicles they can indulge in unsafe behaviours without putting their life unduly at risk. The study provides at best weak support because the authors’ observations have a simpler explanation: variation in personality or other traits linked to car choice and behaviour in the car. The study would be convincing if drivers were randomised to cars rather than being allowed to select them themselves. There is a strong chance that traits that affect decisions about which car to buy also affect in-car behaviour. For example, people in their 60s are less likely to own a sports utility vehicle than those in their 30s and to use a mobile phone at any time (whether in the car or not). Sex is another likely confounding factor, as are numerous personality traits. (Author/publisher)
Abstract