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39 about specific carrier practices (safety managers only), MOTOR CARRIER SAFETY MANAGER SURVEY METHODS and questions about respondents themselves and their organizations. Opinion questions were subjective and This section describes methods specific to the safety man- called for subjective, judgmental responses, mostly in ager surveys. Safety managers were the respondent group of the form of Likert scale ratings. It is important that these greatest interest for the study. These individuals have com- responses not be misinterpreted as objective facts. Ques- pany titles such as Safety Manager, Safety Director, Director tions about specific carrier practices used (yes-no) were of Compliance, and Vice President for Safety (and/or Com- on the safety manager survey forms only. Questions about pliance). A few have titles relating to HR management or the respondents themselves (e.g., years of experience) operations. The respondent pool (sample space) consisted were also objective. All of the caveats on sample repre- of individuals participating in national industry groups sup- sentativeness apply to all questions on both forms. Thus, porting safety, or who had attended safety meetings and none of the survey results on either form can be general- whose contact information was available to the project team. ized to larger respondent groups or populations such as As discussed in the previous section, this pool may be char- "North American carrier safety managers" or "experts acterized as representing safety-conscious carrier safety and in motor carrier safety." The value of the survey results HR managers who are willing to participate in such research. is not based on representativeness to larger populations, All of the sampling and data analysis issues discussed in the but rather on respondents' answers to specific questions previous section apply to the safety manager survey. relative to other, similar questions (e.g., Which personal traits were rated most relevant to crash risk? Which safety Questionnaire Design and Content practices were rated as most effective?). The safety manager survey questionnaire is provided in Nonuse of Response Percentages Appendix A. It consisted of the following general sections: Per CTBSSP policy, the survey results tables in this chap- A brief statement of the study and survey purpose, with ter, and survey results cited elsewhere in this report, do not a confidentiality assurance include results percentages. Instead, raw numbers are cited. Two related five-choice questions on general factors This practice reduces the likelihood that survey results will affecting safety and crash risk (used on paper form only) be misinterpreted or incorrectly cited as representing larger Two related five-choice questions on carrier practices respondent populations. Readers may generate their own affecting driver crash risk percentages, but it is important that they be stated as being Twelve driver personal/psychological traits, each rated representative of larger groups. on a one- to five-point Likert scale for association with crash risk Likert Scale Means Thirteen carrier driver hiring practices, with a two- part answer for each: Likert scales are numeric rating scales, often with five Yes-no for whether the practice was used by the choices numbered from 1 to 5. Likert scales usually have manager's fleet word descriptors for each choice, or "anchor" choices at the If yes, a one- to five-point Likert scale to rate the ends and perhaps the middle. Two different Likert scales practice's safety effectiveness were used in project surveys: A single question on the carrier's planned use of the Pre-Employment Screening Program (PSP) A five-point scale relating driver personal/psychologi- An open "comments" space cal traits to crash risk. Choices ranged from "little or no Four questions on respondent's professional experi- association (1)" to "very strong association (5)." ence and fleet characteristics A five-point scale rating the effectiveness of driver hir- A space for an optional e-mail address to which to send ing practices. Choices ranged from "highly ineffective the project report PDF file (1)" to "highly effective (5)." A space to volunteer for a paid interview on innovative carrier practices for the project case studies. Results are provided in the form of respondent counts for each choice along with the weighted arithmetic mean of The paper version of the questionnaire (administered all choices. TRB's online survey service provided these sta- principally at a truck and a bus trade association meeting) tistics automatically in survey reports. For paper surveys, contained all of the previously mentioned sections. The the survey statistics were obtained from Excel spreadsheets online version was streamlined slightly by omitting the ini- used to enter and reduce the data. tial two questions on crash risk factors.