Final answer:
Personal interviewing is the most expensive survey method due to the high logistics, transportation costs, and labor involved.
Step-by-step explanation:
Among the survey methods listed, personal (face-to-face) interviewing is generally the most expensive. Reasons for the high cost include the logistics of randomly selecting households or polling locations, transportation costs, the time spent on multiple attempts to reach respondents, and the hiring and training of interviewers. Field research in person is time-consuming and therefore costly. In contrast, mail surveys may seem expensive due to printing and postage costs, but they typically do not involve travel or in-person interaction costs. Telephone surveys, especially those using random-digit-dialing, can be cost-effective but less so than internet surveys, which have minimal distribution costs and can reach a wide audience quickly and inexpensively. Nevertheless, all methods must be designed carefully to ensure accurate and representative results.