Participants recruited for driving simulator studies may need to be excluded if they fail to complete thestudy as designed. The data that is analyzed therefore includes a sampling bias that is not typicallyconsidered but important to recognize. This sampling bias was examined using a study involving five datacollection sites in the US. The goal of the original study was to examine the effectiveness of a forwardcollision warning system. A distracting task is part of the study protocol to divert drivers’ attention awayfrom the braking lights of the forward vehicle. In this experiment, two groups of participants becameineligible for further data analysis: (1) conservative drivers who had difficulty being artificially distractedand (2) risky drivers who did not maintain vehicle control while distracted. Two separate binary logitmodels were used to identify factors associated with these two driver types. As age increased, drivers weremore likely to be in one of these driver types and are therefore, likely to be disqualified from furtherexamination. Females had a higher likelihood of losing control during the distraction task when comparedto males. Further, drivers with previous driving simulator experience were better able to maintain vehiclecontrol while distracted. Drivers in two (Iowa City, IA and Seattle, WA) of the five sites were less likely tobe distracted. The sampling biases observed among older drivers and female drivers may have implicationswith respect to the generalization of the findings. The site differences observed may be indicative ofordering effects in that IA and WA were the first two sites to begin data collection. Once issues withattrition became apparent, there was a greater emphasis on the experimental training in the latter datacollection sites.
展开▼
