The following is a modified excerpt from Applied Qualitative Research Design: A Total Quality Framework Approach (Roller & Lavrakas, 2015, p. 51).
The research in-depth interview (IDI) method has been compared to interviewing styles employed outside of qualitative research—such as the interviews used in journalism, psychotherapy, and law enforcement—with the assertion that “there are not necessarily hard-and-fast distinctions 
between these interview forms” (Brinkmann & Kvale, 2015, p. 4). It is true that, in every case, the IDI consists of an interviewer who enters into a one-on-one dialogue with an interviewee in order to discover some aspect of personal information about and from the interviewee. The interviewer is typically in control of the questions that are asked and, when the interviews are completed, the information is analyzed in order to create a story or narrative that conveys an understanding of some topic of interest. Whether it is an interview with a cancer survivor in a qualitative IDI study, the new city mayor for the local newspaper, a psychotherapist’s request for more details related to the patient’s mood disorder, or a police detective’s interrogation of a crime suspect, the IDI approach is “the method by which the personal is made public” (Denzin, 2001, p. 28) to the researcher and the information is used to convey a story about a person or phenomenon.
The qualitative research IDI does, however, differ from these other forms of interviews in two important aspects: the goals of the interview and the interviewing strategy. Whereas the goal of the journalist is to gather the facts for a news story, and the psychologist’s objective is to alleviate an individual’s mental suffering, and the police detective interviews witnesses and suspects to eventually gain a confession, the qualitative researcher conducts IDIs to obtain intricate knowledge, from a small number of members in a target population, based on a well-thought-out research design constructed to maximize credible and analyzable outcomes. Research IDIs are ultimately utilized to make changes or improve the lives of the target population as well as other target groups in similar contexts. With divergent interviewing goals, it is no wonder that qualitative researchers employ interviewing strategies that are partially at odds with especially those of the journalist or detective.
Interviewer training in the unique and necessary skills and techniques associated with the IDI method is mandatory. Unlike other variations Read Full Text
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of the process. The relative closeness of the interviewer–interviewee relationship that is developed in the IDI method potentially increases the credibility of the data by reducing response biases (e.g., distortion in the outcomes due to responses that are considered socially acceptable, such as “I attend church weekly,” acquiescence [i.e., tendency to agree], and satisficing [i.e., providing an easy “don’t know” answer to avoid the extra cognitive burden to carefully think through what is being asked]) and nonresponse, while also increasing question–answer validity (i.e., the interviewee’s correct interpretation of the interviewer’s question).