What type of data collection method does the Delphi technique primarily utilize?

The Delphi technique primarily utilizes self-administered questionnaires as its data collection method. This technique involves the gathering of expert opinions and feedback on a specific topic through a series of structured questionnaires administered in multiple rounds. Participants typically respond to questions in writing, allowing them to contemplate their answers without time pressure and to remain anonymous. This anonymity helps reduce the influence of dominant individuals during discussions and encourages more honest and thoughtful responses.

The iterative process of sending these questionnaires in multiple rounds allows researchers to refine responses, converge toward consensus, and explore differing viewpoints in depth. By utilizing self-administered questionnaires, the Delphi technique not only facilitates in-depth qualitative insights but also helps in collecting quantitative data from experts, which can then be analyzed statistically if required.

The other options represent data collection methods that do not align with the fundamental structure of the Delphi technique. Large-scale surveys with random sampling focus more on gathering broad data from a diverse population rather than expert opinions. Face-to-face interviews typically involve direct interaction, which contrasts with the anonymity that the Delphi method ensures. Experimental manipulation of variables relates to establishing cause-and-effect relationships in controlled environments, which does not match the exploratory and consensus-building nature of the Delphi technique.