Survey researchers employ a variety of techniques in the collection of survey data. People can be contacted and surveyed using several different modes: by an interviewer in-person or on the telephone (either a landline or cell phone), via the internet or by paper questionnaires (delivered in person or in the mail).

The choice of mode can affect who can be interviewed in the survey, the availability of an effective way to sample people in the population, how people can be contacted and selected to be respondents, and who responds to the survey. In addition, factors related to the mode, such as the presence of an interviewer and whether information is communicated aurally or visually, can influence how people respond. Surveyors are increasingly conducting mixed-mode surveys where respondents are contacted and interviewed using a variety of modes.

Survey response rates can vary for each mode and are affected by aspects of the survey design (e.g., number of calls/contacts, length of field period, use of incentives, survey length, etc.). In recent years surveyors have been faced with declining response rates for most surveys, which we discuss in more detail in the section the problem of declining response rates.

In addition to landline and cell phone surveys, the Pew Research Center for the People & the Press also conducts web surveys and mixed-mode surveys, where people can be surveyed by more than one mode. We discuss these types of surveys in the following sections and provide examples from polls that used each method. In addition, some of our surveys involve reinterviewing people we have previously surveyed to see if their attitudes or behaviors have changed. For example, in presidential election years we often interview voters, who were first surveyed earlier in the fall, again after the election in order to understand how their opinions may have changed from when they were interviewed previously.

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