Sample Surveys

7. Collecting Data

When designing a scientific survey, methods for each step of the data collection process must be carefully specified. The data collection process, which involves contacting and recruiting a respondent and then collecting the data, differs somewhat for interviewer- and self-administered surveys.

For interview-based surveys

  • The first step often begins with advanced notification via a letter describing the purpose of the survey and respondent rights.
  • The next step is to contact the sampled unit (e.g., household) to explain the survey and respondent rights again and request participation in the survey. The contact process generally involves repeated contact attempts (often 12 or more) on different days and at different times of day, as well as ad hoc searches for updated telephone numbers or addresses.
  • Depending on the type of survey, verbal or written consent may be needed from adult respondents or by parents on behalf of child respondents. If the respondent refuses initially, then a later attempt to recruit the respondent may be made.
  • If the respondent agrees to participate, there may be screening process to determine eligibility and possibly a selection process such as randomly sampling an adult from the household.

Once these steps are completed, the interview takes place using the questionnaire.

Figure 1

Figure depicting data collection process; select sample, send advanced notification letter, make initial contact, screen and obtain consent, collect data.