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30 CHAPTER THREE SURVEY METHODS AND RESULTS Chapter two reviewed research and trade literature on rel- accurate respondent contact information likely to result in a evant principles and specific practices relating to carrier satisfactory survey return rate. operational efficiency and safety. An additional method for obtaining information for this study was project surveys. Two The safety-manager sample consisted of individuals par- similar survey forms were used for two different respon- ticipating in trade associations or national meetings relating dent groups. Most important was a survey of current CMV fleet to motor carrier safety. The e-mail addresses of these individ- safety managers. The safety-manager survey asked respon- uals were known to the project team, or paper survey forms dents their opinions on safety effects of operational practices, were distributed directly to them in trade association meetings. what practices they used, and their ratings of their effectiveness. The sample is presumed here to be strongly biased toward orga- Of secondary importance, but still of interest, was a survey nizations and individuals with more experience, past success, of other experts in motor carrier safety. This survey form safety sophistication, and safety conscientiousness than the addressed the same general topics, but was limited to opinions overall population. because the respondents were not current practitioners. The two survey forms are provided in Appendix A. This chapter Those returning the survey (whose responses are presented describes the survey approach and specific methods, and pro- here) are the respondents. Just as the sample space was likely vides principal results for each respondent group. Results for a biased slice of the population, the sample was likely a biased the two respondent groups are presented separately because slice of the sample space. That is because in most surveys, of their different perspectives on the problem, and because the those responding tend to be more committed and interested two forms differed somewhat in their questioning approaches in the topic than those not responding. Moreover, they tend to and in specific content. be more educated and verbal (Walonick 2010). Both sources of bias almost certainly operated, and operated strongly, in the A general caveat regarding most of the survey responses present safety-manager survey and, perhaps to a lesser extent, is that they represent subjective responses to subjective in the other-expert survey. questions. A few questions were objective (e.g., questions asking safety managers whether or not they use a particular A larger study focusing on the survey per se likely could safety management practice), but most called for subjective do a better job of capturing the larger population, increas- judgments by respondents. Another caveat is that both sam- ing the size and representativeness of the sample space, and ples must be regarded as convenience samples of interested, obtaining a higher survey response rate. Study resources did knowledgeable individuals, not as representative samples of not permit a more extensive, rigorous, and layered subject larger populations. Conceptually, both the safety-manager sampling approach. The obtained sample, even if represent- and other-expert populations are amorphous and are not cap- ing a skewed sample of the most knowledgeable and safety- tured by any list. In addition, the safety-manager popula- conscious respondents, still provided valuable information, tion is extremely large (in the hundreds of thousands in the however, for the following reasons: United States), diverse, and problematic from the sampling perspective. It tapped the views and practices of industry leaders. It provided information on the subjects' relative opinions on the various operational risk factors and practices OVERVIEW OF SURVEY APPROACH, ANALYSIS, presented. AND INTERPRETATION It provided contacts for follow-up interviews with safety managers regarding the practices of safety-active Sampling Approach companies. The conceptual population for the safety-manager survey was North American motor carrier (truck and bus) safety managers. Data Analysis and Interpretation This population is somewhat amorphous, as there is no con- sistent definition or criterion for "carrier safety manager." There were three general types of questions on the surveys: Also, there is no central potential respondent list that could questions about respondent opinions, questions about specific be used as the basis for systematic sampling or as a source for carrier practices (safety managers only), and questions about