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47 CHAPTER SEVEN CONCLUSIONS A number of conclusions and findings were derived from the collecting databases of target population e-mail addresses, writing of this synthesis. First, transit researchers are con- particularly those of current riders. Developing a representa- ducting their research in ways that indicate foresight and tive sample database of riders and potential riders in the tran- thoughtfulness. Specifically, transit researchers are already sit agency's geographical area combined with the strengths implementing many of the successful practices described in of web-based survey methods can give transit researchers this report, such as: powerful options to conduct effective research quickly and inexpensively. Starting simply with web-based surveys to learn the differences between such surveys and other survey Web-based surveys have limitations as well as strengths, as methods. do all survey methods. Therefore, the strengths and limitations Attempting to compile databases of e-mails from cus- of all applicable survey methods should be weighed together tomers and potential customers to use as a sampling when undertaking transit research. For example, although source for research. web-based surveys have more coverage error compared with Applying web-based survey methods in a multi-method telephone surveys, they generally have better nonresponse survey environment to improve response rates by pro- error than telephone surveys. Both types of errors should be viding response alternatives and to enable transit considered when conducting research. Furthermore, survey researchers to gain the benefits of web-based survey methods can be used in conjunction with each other to ensure data and techniques. the best research possible. For example, using targeted web- Researching the issue of coverage error and trying to based surveys for certain hard-to-reach populations such as minimize sampling bias in their studies. high-income, busy professionals, while using other survey Remaining cautious but optimistic about including methods to reach other populations in the sampling frame, is web-based surveys in their research programs as web- often beneficial to the study and still cost-effective. based survey methods and the Internet mature. Ideas for further research that have been generated through Although web-based surveys have already made some this synthesis effort include understanding clearly how much inroads into the culture of transit research, it appears that use more effective it is to add an additional survey method to a of web-based surveys will become more significant in tran- study and under what conditions. Whereas adding an addi- sit research in the next few years. Based on the survey con- tional survey method can be more convenient for respondents ducted for this synthesis, only 39% of researchers indicated of paper surveys, the additional cost of adding other survey they are conducting web-based research. However, as noted methods to a study may or may not be worthwhile; therefore, in the report, 70% of those who are not conducting research research in this area could be quite interesting. believed that they probably would be doing so within the next two years. Therefore, it is still early for web-based sur- Another issue that has been difficult to quantify is the effect veys in transit; however, in the near future, it appears web- of spam filters on survey invitations. It would be helpful to based survey methods will both be used by a significantly research how to avoid spam filters and to understand what larger proportion of transit researchers and likely be used types of populations are likely to block survey invitations and more often and more prominently by researchers who are whether this generates a problematic nonresponse bias. currently using web-based surveys. The issue of establishing credibility using web surveys is Owing to the likely increase in the use of web-based sur- another topic worthy of future research. Research into how veys, a major conclusion from this synthesis is that transit to protect potential respondents' information so that they are researchers should be measuring the Internet penetration assured that their data will be transmitted securely, kept con- among their target populations so that coverage error can be fidential, and not sold to third parties is very important to understood and mitigated. enhance the credibility of web-based research. The ability to prove to respondents that the survey agency requesting their Another conclusion, along with coverage measurement, is participation is a legitimate organization and not a front for that transit agencies and other transit researchers should be some sort of scam is also critical. Some of these credibility

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48 issues were raised in this synthesis; however, further research define, but only to a certain level. If there is interest in the could be helpful to cover this topic more comprehensively. transit community, developing a very detailed and compre- hensive tool kit for exactly how to develop a web-based Finally, the topic of web-based surveys in transit contains research program could be undertaken as a future research many issues that this synthesis has been able to identify and endeavor.