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On-board and intercept surveys are used by virtually all transit agencies to collect data on customer trip characteris- tics, customer ridership and demographic characteristics, and customer attitudes about service. Survey results are used for a wide variety of purposes including travel modeling, areawide and route planning, scheduling, marketing, and customer communications. Transit agencies reported that survey results can be highly useful, accurate, and timely. On-board and intercept survey methodologies are essen- tial to transit agencies in a variety of situations. These methodologies may be the only cost-effective way to gather information from riders where the incidence of transit users in the general population is low. In major cities with a high incidence of transit users among the citizenry, on-board and intercept methodologies are highly useful for surveys on specific routes or among specific customer segments. Other major strengths of on-board and intercept surveys include the ability to obtain a representative sample of the targeted population; the wherewithal to obtain accurate, reliable, and detailed information from riders; and the means to survey during the immediate experience of the service. On-board and intercept surveys often provide higher response rates than alternative methodologies such as telephone, mail, and on-line surveys, and at lower cost. Although offering many advantages, on-board and intercept surveys are not the optimal methodology in a variety of situa- tions. Telephone or other methodologies are necessary when the objective is to survey non-users. On-board and intercept surveys also cannot be used when the survey questionnaire is extensive or complex. Surveys are typically returned to survey workers, but may also be deposited in envelopes or boxes on board or through the mail. Self-administered surveys are sometimes distributed at transit centers and transfer points instead of on board. This approach is particularly suitable when most or all of the study population passes through the survey locations. On occasion agencies use personal interviews instead of self-administered surveys. Personal interviews can be con- ducted either on-board or in rail stations, transit centers, or at transfer points. The interviews are generally relatively brief. 60 Personal interviewing tends to achieve a higher response rate, fewer item nonresponses, and possibly better under- standing of questions than self-administered surveys. On-board and intercept surveys are highly flexible and adaptable to the project purposes and characteristics of the agency's service configuration and of the study population. Given the need to tailor survey methodology to the particu- larities of the situation, there is no uniform way to carry out on-board and intercept surveys. In designing a survey to fulfill project objectives, maximize data quality, and control costs, a number of factors need to be considered. Important considerations relating to project purposes include: ⢠What is the study population?âWhether the study pop- ulation is all riders, riders on a particular route, or those using a particular station will affect the choice of on- board versus in-station locales. ⢠What amount and level of detail of information is needed?âLonger surveys need to be conducted in situations where respondents have sufficient time to complete the survey for immediate return or are likely to complete the survey at a later time for return through the mail. The ability of respondents to provide accurate detailed information and the level of accu- racy needed will affect the choice of personal inter- views or self-completed surveys. ⢠What aspects of the customer experience does the survey ask about?âFor example, surveys may need to take place proximate to customersâ experience of a ticket vending machine. Considerations affecting data quality are: ⢠Response ratesâResponse rates affect the amount of nonresponse error, which arises from the possibility that those not completing a survey would have answered differently than those who did complete a survey. Response rates are affected by a broad range of factors including the enthusiasm and diligence of sur- vey workers who distribute questionnaires or conduct interviews, the level of rider interest, whether self- administered surveys or personal interviews are used, length and complexity of the questionnaire, use of incentives, and the frequency of surveys being con- ducted. Other factors, less subject to transit agency influence, are rider income, education level, and other demographic characteristics and rider literacy levels. CHAPTER EIGHT CONCLUSIONS AND FURTHER RESEARCH
61 ⢠Clarity and organization of the questionnaireâWord- ing of questions, question ordering, and layout can affect the ease of completing the questionnaire and the accuracy and completeness of responses. ⢠How and where the survey is conductedâData quality is affected by whether self-completed questionnaires or per- sonal interviews are used, where the surveying is carried out, and the means of returning self-administered surveys. Costs for on-board and intercept surveys vary widely, even for surveys conducted using nearly identical method- ologies. Factors that affect costs are: ⢠Whether the survey is conducted by personal interview or uses self-administered questionnaires. ⢠Length and complexity of the survey. ⢠Whether the survey collects detailed origin and desti- nation surveys, which tend to incur higher costs for geocoding and data processing. ⢠Total number of completed surveys (larger surveys may benefit from economies of scale). ⢠Density of riders (e.g., number of riders per hour on surveyed bus or train routes or in stations). ⢠Response rates. ⢠Whether self-administered questionnaires are distrib- uted by dedicated survey staff or bus operators. Planning and implementing surveys also involves deci- sions about identifying the study population and selecting the sample; determining the sample size needed for the desired level of precision in the results; and stratification and weight- ing of subgroups being surveyed based on route, time of day, direction, and other factors. Additional important tasks are recruitment, training, and supervision of survey workers; ensuring worker safety; and data cleaning, data processing, data tabulation, and analysis. In on-board and intercept surveys, the devil is in the details. Although transit agencies have developed many effective practices through experience, there is insufficient methodologically sound research to guide decisions in two key areas: (1) impact of design and layout of questionnaires and (2) impact of the use of incentives. Additional research is needed to explore these two issues. The research should formulate and test different questionnaire designs and different incentive levels to measure the affects of these factors on response rates, item nonresponse, and, for origin and destination information, the quality of address and trip information. Alternative designs could also be tested to determine the impact of questionnaire length, use of matrixes, and use of horizontal versus vertical lists of answer choices. Ideally, alternative questionnaire designs and incentive levels should be tested on routes (or stations) where charac- teristics of the sampled population are held constant, to derive reliable conclusions about the impacts, if any, of alter- native layouts and incentive levels.