Dillman says that both mail and telephone surveys are considered as the “stepchildren” of survey research and not as valuable as interview studies. He formulated something called the “Total Design Method” which enables the mail and telephonic surveys to achieve their full potential. There are two parts to the TDM; they are (a) a theoretical part, which explains the specifications of the research process and responses, (b) the practical part, which explains the detailed parts of the survey process. He also bought in the concept of social exchange, which states that a person would exhibit the same behavior as one exhibits on them. Hence, he said that the key concepts in the theoretical part of the TDM are cost, reward, and trust. All three concepts work in sync to give rise to the theoretical part of the TDM, whereas the practice may just be the observance of the interviewee.
Bailey, K. (1994). Survey Sampling in Methods of social research. Simonand Schuster, 4th
ed. The Free Press, New York NY 10020.Ch-5. Pp. 81-104.