6. Developing a Survey Instrument
Multiple-mode surveys are increasingly common as a means to improve the chances of contacting and recruiting respondents, reduce study costs, or collect different kinds of information. For example, a longitudinal survey in which a household is contacted several times over a time period may begin as an in-person survey for the first contact, but once rapport and familiarity with the survey is established, subsequent contacts are made via phone to save costs. Alternatively, to reduce field costs, a survey may involve an initial telephone interview and then an in-person follow-up phase to obtain physical measurements on an individual who has completed the telephone interview. A telephone survey may also have a mail follow-up phase to obtain more sensitive data in a self-administered mode or as an alternative contact strategy for respondents that are hard to reach during normal calling hours. Figure 1 illustrates 3 possible options for initial contact and follow-up.