Is it finally time to kill self-report outcome measures in road safety? An investigation of common method variance in three surveys of a cohort of young drivers that included the Driver Behaviour Questionnaire.
In his challenging book on road safety research methods, Anders af Wåhlberg (2009) makes a strong case that there are significant, unaddressed problems in the use of self-report measures in road safety research. These include the effects of social desirability and response patterns that contribute to the common method variance largely ignored by road safety researchers. His argument, perhaps overstated, is that the problems associated with self-report measures such as survey questionnaires and the Driver Behaviour Questionnaire (DBQ) are so great that they should not be used in individual-differences research in road safety. This paper reports on an investigation of common method variance in relation to the DBQ, with a particular focus on social desirability effects. Survey data collected from three survey waves of a young driver cohort were analysed to investigate the relationships between measures such as self-reported behaviour, self-reported crash involvement, the DBQ, and a measure of social desirability. The results of these analyses were then used to draw some conclusions about the validity of af Wåhlberg’s concerns and the prognosis for self-report methods.