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Summary of Recommended Standardized Procedures and Guidelines 21 Unit non-response is a significant and growing problem in household travel surveys. A num- ber of standardized procedures and guidelines are recommended as a means to attempt to reduce this phenomenon. Some of these overlap or duplicate those found elsewhere in this report. The following standardized procedures are recommended: 1. Use pre-survey monetary incentives. The positive effect of incentives has been clearly demonstrated in the research reviewed and undertaken here. In contrast to the findings of Section 2.2.8, it appears that larger incentives may be required to convince those who usually refuse or terminate the survey to complete it. This may require a second round of attempts to convert non-responders to responders in which a higher incentive is offered to induce conversion. 2. Use a pre-notification letter and reminders. Special care is required in formulating the pre- notification letter so that it is simple in language, appealing to a wide range of people, and clearly sets forth the importance of responding. Care must also be taken in determining who should sign the letter and in the affiliations shown in the letterhead used. 3. Special train interviewers. Where interviewers are used, special training of interviewers has been shown to have substantial effects on response. Therefore, considerable effort should be paid to developing thorough and complete training of interviewers. 4. Increase efforts to contact households that are difficult to contact. This may be done by increas- ing the number of calls for non-contacted units, designating specific times to call non- contacted units, expanding the data collection period, and conducting face-to-face interviews. 5. Undertake non-response surveys. Non-response surveys should be undertaken as a standard ele- ment of all household travel surveys, rather than as the exception that is the present situation. The following guidance is also offered, based on the research undertaken on this topic: 1. Efforts should always be undertaken to reduce respondent burden in the design of any survey. This often has more to do with the ease with which people can complete the survey task than the actual length of the survey per se. 2. Shorter surveys should be used wherever possible. This raises difficult issues as the need for more detailed data emerges in the transportation profession. Pilot surveys offer a useful mechanism for testing alternative designs, and focus groups should also be used in the design process to determine how to make a survey design shorter while still being effective. 3. Options should be provided on how and when to respond. These options appear likely to increase the number of terminators who will complete the survey. However, more research is needed on the effect of mixed-mode surveys. 2.2.7 D-10: Initial Contacts The subject of this section is the first contact made with a potential respondent in a survey. Contact can be by telephone, mail, e-mail, or possibly even personal interview. In telephone surveys and personal interviews, it involves the very first few words uttered following contact with a prospective respondent. When the initial contact is by mail, it is the envelope in which the material is mailed, the documentation in the envelope, and the opening sentence on the cover letter. The primary need is to design the introduction to surveys in such a fashion that refusals are avoided as much as possible. Currently, the proportion of refusals that occur during initial con- tact is surprisingly high. The factors that influence the rate at which people hang up seem to have received relatively little research in the past. Further discussion of this is to be found in Section 5.7 of the Technical Appendix. Standardized procedures on script formulation would be advantageous in limiting the grow- ing trend in hang ups with telephone surveys. However, further research is required before any