The External Validity of Psychometric Testing Methods and Their Meaning for Safe Road Performance

Abstract

The aim of the paper is to investigate which psychometric tools commonly used by Polish transport psychologists appropriately measure necessary abilities of professional drivers. According to Levis-Eva ns' differentiation between the driver 's performa nce and the driver's behavior, we explored a statistical relation between the results of tests currently used by transport psychologists, measured according to Szalma's individual differences and safe behaviors on roads. We examine validity of tests using data based on real professional drivers' behavior. The sample included 200 drivers involved in accidents and collisions, and 100 who behaved safely. We tested external validity of chosen psychometric tools by analyzing statistically the relation between test scores and unsafe driving behavior recorded by the police. The results show that only few mea surements are valid for differentiation of safe and unsafe drivers. The paper indicates the methodology to reach the prognostic value of the diagnostic tests employed by transport psychologist. Key words: safety behavior, external validity, transport psychology Theoretical BackgroundSince the time when psychologists became interested in road transportation, numerous psychometric tools, including cognitive ability tests and psychomotoric ones have been developed to diagnose individuals applying for a driver's license. This interest in testing these applicants appears already in the classic Münsterberg's book on industrial psychology (Münsterberg, 1913). From this analysis, however, the following question arises: which psychometric tools most appropriately measure abilities that predict safety-related human behavior in road traffic situations? Szalma (2009) argues that individual differences in human factors/ergonomics should be incorporated into research and practice. Within traffic and transport psychology, different research approaches have attempted to explain individual differences in risky driving behavior and traffic accident involvement, which assumes more complex processes and such factors as: aggressive driving