Answer: In-depth interviews
Explanation: In-depth interviews are the interviewing sessions that is conducted with an individual in intensive manner for research. The main aim of doing this king of interview is based on exploring the major idea about the matter or subject.
The interview is held with less number of people so that complexity factor does not disrupt the interview and the perspective of the program.It is a fast process of interviewing and makes the topic to be understood deeply.
Randall should also use in-depth interviewing technique for the structured survey.