Personality versus traffic accidents; meta-analysis of real and method effects

- Heterogeneous effect sizes indicate strong method effects in personality-accident studies.
- Personality dimensions explain less than 1% of variance in accident records.
- No reliable evidence for common method variance.

ProblemThe association between personality and traffic accident involvement has been extensively researched, but the literature is difficult to summarise, because different personality instruments and statistics have been used, and effect sizes differ strongly between studies.MethodA meta-analysis of studies which had used measures of personality which could be converted into Big Five dimensions, and traffic accidents as the dependent variable, was undertaken.AnalysisOutlier values were identified and removed. Also, analyses on effects of common method variance, type of instrument, dissemination bias and restriction of variance were undertaken.ResultsOutlier problems exist in these data, which prohibit any certainty in the conclusions. Each of the 5 personality dimensions were predictors of accident involvement, but the effects were small (r < .1), which is much weaker than in a previous meta-analysis. Effect sizes were dependent upon variance in the accident variable, and the true (population) effects could therefore be larger than the present estimates, something which could be ascertained by new studies using high-risk samples over longer time periods. Newer studies and those using Big Five instruments tended to have smaller effects. No effects of common method variance could be found.ConclusionsTests of personality are weak predictors of traffic accident involvement, compared to other variables, such as previous accidents. Research into whether larger effects of personality can be found with methods other than self-reports is needed.