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38 CHAPTER FOUR SURVEY METHODS AND RESULTS Chapters two and three reviewed research and trade lit- as there is no consistent definition or criterion for "carrier erature on driver individual differences and selection tests safety manager." Also, there is no central potential respon- and measurements, respectively. An additional vehicle for dent list on which to base systematic sampling. obtaining information for this study was project surveys. Two similar survey forms were used for two different respondent The safety manager sample consisted of individuals par- groups. Most important was a survey of current CMV fleet ticipating in trade associations or national meetings relat- safety managers. The safety manager survey asked respon- ing to motor carrier safety. The e-mail addresses of these dents their opinions on driver risk factors, what selection individuals were known to the project team, or paper survey practices they used, and their ratings of the effectiveness of forms were distributed directly to them in trade association these practices. Survey opinions are not taken as empirical meetings. The sample is presumed to be strongly biased facts, but rather as indicators of industry thinking on safety toward organizations and individuals with more experience, management questions. Of secondary importance, but still past success, safety sophistication, and safety conscientious- of interest, was a survey of other experts in motor carrier ness than the overall population. safety. This survey form addressed the same general topics, but was limited to opinions because the respondents were Those returning the survey (whose responses are pre- not current practitioners. The two survey forms are provided sented here) are the respondents. Just as the sample space in Appendix A. This chapter describes the survey approach was likely a biased slice of the population, the sample was and specific methods, and provides principal results for each likely a biased slice of the sample space, because those respondent group. Results for the two respondent groups are responding tend to be more committed and interested in the presented separately because of their different perspectives topic than those not responding. Moreover, they tend to be on the problem and because the two forms differed some- more educated and verbal (Walonick 2010). Both sources of what in their questioning approaches and content. bias operated strongly in the present safety manager survey and to a lesser extent in the "other expert" survey. A general caveat is that most of the survey responses represent subjective responses to subjective questions. A A larger study focusing on the survey per se might be few questions were objective (e.g., asking safety managers better able to capture the larger population, increasing the whether they use a particular safety management practice), size and representativeness of the sample space and obtain- but most called for subjective judgments by respondents. ing a higher survey response rate. Study resources did not Another caveat is that both samples must be regarded as permit a more extensive, rigorous, and layered subject sam- convenience samples of interested, knowledgeable indi- pling approach. The sample obtained, even if it represents a viduals, not as representative samples of larger populations. skewed sample of the most knowledgeable and safety-con- Conceptually, both the safety manager and "other expert" scious respondents, still provides valuable information and populations are amorphous and not captured by any list. In accomplished the following objectives: addition, the safety manager population is extremely large (in the hundreds of thousands in the United States), diverse, · It tapped the views and practices of industry leaders. and problematic from the sampling perspective. · It provided information on subjects' relative opinions on the various traits and practices presented (e.g., which personal traits are rated most safety-relevant by OVERVIEW OF SURVEY APPROACH, ANALYSIS, AND respondents). INTERPRETATION · It provided contacts for follow-up interviews with safety managers on the practices of safety-active companies. Sampling Concept Data Analysis and Interpretation The conceptual population for the safety manager survey was North American motor carrier (truck and bus) carrier There were three general types of questions on the sur- safety managers. This population is somewhat amorphous, veys: questions about respondent opinions, questions