Understanding the science and art of in-depth interviews
A comprehensive guide to the qualitative research method.
In-depth interviews in qualitative research often play a central role in understanding human behavior and experiences. These conversations are typically conducted individually and are designed to explore an individual’s experiences, perspectives, interpretations, and emotions in depth.
This qualitative method encourages participants to share personal stories, which adds context to their responses. The detailed information gathered through these interviews can help inform theories, enhance practices, and guide decision-making across various fields.
When conducted and interpreted rigorously, in-depth interviews can generate contextualized accounts that help researchers understand how people experience, interpret, and respond to complex issues.
This article delves into the art and science of in-depth interviews. The entire series comprises three articles:
- Part 1: Understanding the science and art of in-depth interviews: A comprehensive guide to the qualitative research method
- Part 2: How do you prepare for in-depth interviews? Tips and best practices for preparing and conducting in-depth interviews.
- Part 3: Analyzing in-depth interviews: Unveiling insights from conversations
This article introduces the principles, characteristics, applications, and practical considerations involved in designing and conducting effective in-depth interviews. The subsequent articles examine preparation and analysis in greater detail, leading to valuable, actionable research insights. Ready to dive deeper into the world of qualitative research?
Understanding in-depth interviews in qualitative research
An in-depth interview resembles a conversation but is designed to explore experiences, meanings, and perspectives in greater depth from the participant’s point of view. This technique has several defining features that enhance its effectiveness and utility.
Traditionally, researchers conduct in-depth interviews one-on-one. This format allows the researcher to focus on the participant’s responses while observing accompanying cues, such as emotions and body language. With technological advancements, researchers increasingly conduct in-depth interviews over the phone, via video calls, or through other digital communication methods. These alternatives expand the geographic reach of potential participants and can be effective when the interview mode fits the research question, participant population, topic sensitivity, and practical context.
An interview is not a neutral window into experience
An in-depth interview should not be treated merely as a means of extracting information that already exists, unchanged, in the participant’s mind. What is said emerges from an interaction between the participant and the researcher, shaped by the questions asked, the interviewer’s responses, their relationship, the research context, and the participant’s own interpretation and memory. Recognizing this does not diminish the value of interview data; it clarifies what such data represent and why careful interviewing and reflexive interpretation are essential.
Characteristics of in-depth interviews
Open-ended questions
In-depth interviewing relies heavily on open-ended questions. Interviews typically begin with clearly defined research objectives and questions, but remain flexible enough to allow participants to introduce issues, experiences, and meanings the researcher may not have anticipated. Rather than prescribing the full range of possible responses, open-ended questions give participants space to describe experiences in their own terms. The interviewer can then use follow-up questions and probes to explore issues that emerge during the conversation.
While researchers may start with a structured outline informed by research goals, they design questions to encourage detailed narratives. They use open-ended questions to elicit thorough, descriptive responses that reveal rich insights. Unlike casual chats with a friend, these conversations aim to build knowledge about a specific topic from the perspective of the individual involved. Interviews are exceptionally well-suited to gaining a deeper insight into people’s experiences.
Gaining these insights largely depends on the participant’s willingness to speak with the researcher. Well-designed open-ended questions can encourage participants to provide detailed responses and extended reflections.
Probing and follow-up
The researcher uses probing and follow-up questions to clarify, elaborate, and explore issues the participant raises. Probes may seek concrete examples, underlying reasoning, contextual detail, emotions, changes over time, or contradictions within an account. Effective probing is responsive rather than mechanical: the interviewer must decide which emerging lines of inquiry are relevant to the research question. Probing techniques are essential for gaining deep insights during qualitative interviews. While open-ended questions often yield broad responses, probing techniques enable researchers to explore participants’ thoughts and feelings more thoroughly. This exploration uncovers nuances that can significantly shape how researchers understand and interpret the collected data.
Interpersonal connection
Building an interpersonal connection to foster comfort and trust is crucial to in-depth interviewing. Establishing rapport can encourage engagement and make it easier for participants to discuss experiences, including sensitive or difficult topics. However, rapport does not guarantee more accurate or candid responses; the interpersonal relationship can also influence what participants choose to disclose and how they present their experiences. Appropriate conversational warmth, attentiveness, and respect can help establish rapport. Depending on the topic and participant, this may involve brief introductory conversation before moving into the research discussion; however, rapport-building should remain appropriate to the research context rather than becoming an objective in itself. A warm, respectful demeanor can signal that participants’ perspectives are valued and may help create conditions for more comfortable engagement.
Skilled interviewers use conversational norms to pursue their research objectives. This can make the interaction feel more conversational, reduce unnecessary pressure, and facilitate discussion of experiences and feelings.
This connection can facilitate richer accounts, but the interviewer must remain attentive to how the relationship itself may shape what is disclosed and how experiences are described.
Emphasis on subjectivity
In-depth interviewing recognizes that participants interpret and describe their experiences from particular social, cultural, historical, and personal positions. The aim is not necessarily to treat each account as an objective representation of reality, but to understand how participants perceive, interpret, and give meaning to their experiences.
Focus on context
In-depth interviews can help researchers understand the social and cultural contexts in which human behavior occurs and how individuals attach meaning to their experiences. They allow researchers to explore issues from the perspective of those who experience them, providing contextual understanding of participants’ behaviors, attitudes, and interpretations.
Rigor and trustworthiness
Rigorous in-depth interviewing requires more than obtaining detailed responses. Researchers should consider how sampling, interviewer behavior, questioning, interpretation, and analytic decisions shape the resulting evidence. Depending on the methodological approach, strategies such as reflexivity, transparent documentation, triangulation, attention to divergent cases, and a clear analytic audit trail can strengthen the credibility and trustworthiness of the findings.
Rich, detailed data
In-depth interviews can generate forms of contextual, experiential, and interpretive detail that standardized surveys are generally not designed to capture. They allow participants to describe their experiences in their own words, generating potentially nuanced accounts of how they understand and interpret those experiences.
Flexibility
In-depth interviews reveal unexpected themes and insights by adapting to the participant’s narrative. These open-ended discussions allow researchers to explore topics emerging during the conversation, leading to surprising discoveries.
Emotional depth
In-depth interviews can explore emotional, experiential, and interpretive dimensions of a topic when these are relevant to the research question. However, participants’ accounts of emotions and experiences remain situated self-reports and should be interpreted within their social and conversational context.
Active listening
Active listening requires engaging with the speaker through focused attention and empathy. By practicing this skill, researchers can demonstrate attentiveness and respect, which may support participant engagement and fuller responses.
Navigating sensitive topics with care
The importance of establishing a safe and respectful environment cannot be overstated. Interviewers prioritize building trust with participants when discussing sensitive subjects to encourage open and honest dialogue. This starts with clear communication about the research purpose, informed consent, and how researchers will handle and protect participants’ information. Thoughtfully preparing questions and using open-ended inquiries allows participants to share their experiences at their own pace. Adopting a neutral stance during discussions ensures a supportive tone while avoiding judgment. Finally, showing empathy and understanding helps participants feel comfortable during challenging conversations.
Why use in-depth interviews?
Interviews are often used as a standalone method or combined with other qualitative methods, such as focus groups or ethnography, or quantitative methods, such as surveys or experiments. They are not suited to every qualitative research question, but their strengths can guide when and how to use them within a research design.
- Use in-depth interviewing techniques when details about an individual’s beliefs, attitudes, and behaviors are critical to a research question, when exploring an issue or process, or when individual narratives can add insight alongside other methodologies.
- In-depth interviews are particularly useful for exploring how people seek, interpret, and use information. They help identify patterns, develop models, or understand how individual experiences reflect broader, collective trends.
- In-depth interviews are helpful when the researcher wants detailed information about a person’s thoughts and behaviors, or when exploring new issues in depth. Interviews can provide contextual explanations that complement other forms of evidence, helping researchers explore participants’ accounts of what happened and how they interpreted it.
When to use in-depth interviews?
In-depth interviews can serve as a data-generation method across a range of qualitative methodologies, including case study, ethnography, phenomenology, grounded theory, and narrative inquiry. However, these approaches differ in their philosophical assumptions, research purposes, sampling strategies, analytic procedures, and standards for interpreting evidence. Therefore, the same interview technique does not carry the same methodological meaning across all qualitative designs. Interviewing does not have a single epistemological position. The methodological and theoretical approach the researcher adopts influences what counts as knowledge, how data are generated and analyzed, and how findings are interpreted.
Defining research scope
In-depth interviews may be used early in a research program to explore an emerging issue, clarify concepts, identify relevant dimensions of a problem, or inform subsequent qualitative or quantitative research. They can also be used later in a research program to explain, contextualize, or challenge findings generated by other methods.
Adding depth to quantitative findings
In-depth interviews can complement quantitative findings by exploring the experiences, interpretations, and motivations that may help explain observed patterns in quantitative data.
Questionnaire refinement
Qualitative interviews can help researchers identify language, concepts, response dimensions, and issues relevant to subsequent surveys. However, when the specific objective is to evaluate how participants understand, retrieve, judge, and answer draft survey questions, cognitive interviewing is the more specialized method.
Alternative to focus groups
In-depth interviews are well-suited to situations where participants may feel uncomfortable discussing specific topics, especially sensitive ones. They are particularly useful when individual disclosure is important or when group interaction could inhibit discussion of sensitive topics. Unlike focus groups, which deliberately use interaction among participants as part of the data-generation process, in-depth interviews provide greater opportunity to examine an individual’s account without the immediate influence of other participants.
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In-depth interviews may also be preferable to focus groups when logistical constraints make group recruitment difficult, such as when participants are geographically dispersed or have unpredictable or demanding schedules.
Phenomenological approach
Phenomenological research seeks to understand how people experience and make meaning of a phenomenon from their lived perspective. In-depth interviews are frequently used because they allow participants to describe experiences in considerable detail. However, phenomenology involves more than conducting in-depth interviews; the philosophical and methodological orientation also shapes sampling, questioning, analysis, and interpretation. The objective is therefore not simply to collect rich narratives, but to examine the meaning and structure of lived experience in accordance with the chosen phenomenological approach.
Grounded theory
In grounded theory, interviews can contribute to the iterative development of concepts and an explanatory account of a social process. Data collection and analysis typically proceed iteratively, with emerging categories informing subsequent data collection and theoretical development. Constant comparison, coding, memoing, and — depending on the grounded-theory approach — theoretical sampling help researchers move from individual accounts toward a conceptual explanation of the phenomenon under study.
Ethnographic research
In ethnographic research, in-depth interviews can complement participant observation and other forms of fieldwork by providing participants’ accounts of practices, meanings, relationships, and experiences that may not be directly observable. Observation can illuminate what people do in context, while interviews can help researchers explore how participants understand and explain their actions. Researchers can therefore combine these two sources of evidence to examine the relationship between observed practices and participants’ interpretations.
Case studies
Within case study research, in-depth interviews can provide detailed accounts of participants’ experiences and perspectives within a bounded case. Interviews may be combined with documents, observations, administrative records, or other evidence to develop a contextualized understanding of the case. Their value lies not simply in the depth of individual narratives, but in how those narratives help explain the phenomenon within its specific context.
Comparing semi-structured vs. free-flowing in-depth interviews
In-depth interviews vary in their degree of structure. At one end are relatively standardized interviews with a defined sequence of questions; at the other are unstructured or conversational approaches in which participants have greater influence over the direction and sequence of the discussion. Semi-structured interviews occupy a middle ground, using a discussion guide to ensure coverage of key topics while allowing the interviewer to adapt questions, probes, and sequencing to the participant’s account. The appropriate level of structure depends on the research question, methodological approach, and need for comparability across interviews.
Relatively unstructured interviews
Relatively unstructured interviews can be valuable when a researcher seeks to understand the broader account surrounding a topic. Their flexible structure allows the researcher to explore complex or emerging issues and follow participants’ accounts in greater depth.
In a relatively unstructured interview, the researcher lets the discussion develop in response to the participant’s account while staying aware of the research objectives. A loose agenda or set of topic areas can provide orientation without functioning as a strict script.
Skilled interviewers can follow a participant’s train of thought and rearrange questions to better align with the flow of the discussion.
Semi-structured interviews
Semi-structured interviews, by contrast, blend guidance and flexibility. These are particularly useful when the researcher has clearly defined objectives and needs some degree of comparability across interviews. The researcher generally covers the same core topics or research domains across interviews, while allowing the wording, sequence, and depth of follow-up questions to vary according to each participant’s responses. They allow enough flexibility to dig deeper while keeping the interview on track to meet research goals.
An interview guide gives the interviewer a schematic outline of the planned conversation and helps keep the interview focused. Questions may include suggested probes and follow-up questions designed to explore specific aspects of an issue.
One common way to structure a discussion guide is to start with relatively easy, open-ended questions. Opening questions should relate to the research topic but be broad and easy to answer, helping ease the participant into the conversation.
After these broad opening questions, the discussion guide may move into topics that speak more directly to the overarching research question. The interview questions will be accompanied by probes designed to elicit concrete details and examples from the participants. For example, questions about feelings can be difficult for some participants to answer, but they become less challenging when followed by probes about factual experiences.
Although the discussion guide helps the researcher stay on track with the broad areas they want to cover, they do not need to feel tied to it. For instance, if a participant raises a theme the researcher intended to discuss later or a point the researcher had not anticipated, the researcher may decide to follow the participant’s lead. The researcher’s role extends beyond simply asking questions; it involves listening and responding, making split-second decisions about which line of inquiry to pursue, and allowing the interview to take unexpected turns.
Interviewer reflexivity
The interviewer is not a neutral conduit for information. Their assumptions, identity, professional background, wording, reactions, interpersonal style, and relationship with the participant can influence what is discussed and how it is expressed. Reflexivity therefore requires researchers to examine how their position and decisions may have shaped the data-generation process. This may involve reflective notes, post-interview debriefs, peer discussion, or maintaining a reflexive journal. The objective is not to eliminate researcher influence — which is rarely possible — but to make that influence visible and analytically considered.
Ethical considerations
Ethical interviewing extends beyond protecting confidentiality. Participants should understand the purpose of the research, what participation entails, how their information will be recorded and used, and their right to decline to answer questions or withdraw, where applicable. Researchers should consider potential emotional, social, professional, or other consequences of participation, particularly when discussing sensitive topics. Recording, transcription, storage, anonymization, and access to interview data should also comply with applicable ethical and data protection requirements.
Advantages of in-depth interviews
The value of in-depth interviews lies not simply in the amount of information they generate, but in the opportunity to examine experiences, meanings, reasoning, context, and processes in depth. Their conversational, flexible structure allows researchers to pursue issues that emerge during the interview and explore how participants interpret their experiences. Interviews can provide an environment in which participants have the time and interactional space to explain experiences in their own words. However, comfort varies by participant, topic, interviewer, and interview mode; the interview setting can also introduce social desirability or other interaction effects.
Disadvantages of in-depth interviews
However, in-depth interviews have a few limitations and pitfalls, each of which is described below. Balancing these advantages and disadvantages is crucial to using in-depth interviews effectively in research.
Time-consuming
In-depth interviews can require substantial time for recruitment, scheduling, interviewing, recording, transcription, familiarization, coding, analysis, and interpretation. The burden increases when interviews are lengthy, samples are heterogeneous, or analysis requires multiple rounds of coding and team review.
Cost
Because in-depth interviews require significant time and resources, they can be more costly than some alternative data-collection approaches, particularly when recruitment, transcription, and analysis are resource-intensive.
Limited statistical generalizability
In-depth interviews typically use purposive or otherwise non-probability sampling and relatively small samples, so findings are generally not intended to provide statistically generalizable estimates for a wider population. Instead, qualitative researchers may seek contextual understanding, theoretical insight, or findings that are transferable to other settings when sufficient contextual information is provided.
Sampling and participant selection
Qualitative interview studies typically use purposive sampling to recruit participants who can provide relevant and information-rich accounts of the phenomenon under investigation. Depending on the research purpose, researchers may seek variation across relevant characteristics, select participants with particular experiences, use criterion-based sampling, or employ theoretical sampling as concepts develop during analysis. The objective is not necessarily statistical representativeness, but a sample that is appropriate to the research question and capable of generating sufficiently rich and relevant data.
Sample size and information sufficiency
There is no universal number of interviews required for an in-depth interview study. Sample adequacy depends on the research question, population, sampling strategy, sample heterogeneity, interview structure, analytic approach, and data richness. Researchers may use concepts such as saturation, information power, or information sufficiency to justify when additional interviews are unlikely to add sufficient value.
Importantly, simply reaching a predetermined number of interviews does not demonstrate that a qualitative sample is adequate. Researchers should explain how and why the final sample was judged sufficient for the specific research purpose.
In some studies, researchers distinguish code saturation, where the range of relevant issues has been identified, from meaning saturation, where sufficient depth and nuance have been developed to understand those issues. Meaning saturation generally requires more than simply identifying recurring topics; it involves developing sufficient depth and nuance to understand the dimensions and meanings associated with those topics.
Participant reluctance
Some participants may be reluctant to disclose personal information, find certain experiences difficult to articulate, or interpret questions differently than the researcher intended. These factors can influence the depth, content, and interpretation of the resulting data.
Potential for interviewer and interpretive bias
Interview data are shaped by the interaction between participant and researcher, and qualitative analysis necessarily involves interpretation. Interviewer characteristics, question wording, probing, expectations, analytic decisions, and selective attention can therefore influence the resulting findings. Rigorous sampling, interviewer training, reflexivity, transparent analytic procedures, attention to divergent cases, and appropriate forms of triangulation can help researchers identify and manage these influences.
Conclusion
In-depth interviews are a versatile qualitative data-generation method for examining how people experience, interpret, and give meaning to issues that standardized measures may not capture with comparable depth. Their value depends not simply on asking open-ended questions, but on the quality of sampling, questioning, probing, listening, reflexivity, ethical practice, and subsequent analysis. A well-conducted interview can produce rich contextual evidence; a poorly designed or insufficiently reflexive interview can produce equally detailed but misleading accounts.
The other articles in this series cover:
- Part 2: How do you prepare for in-depth interviews? Tips and best practices for preparing and conducting in-depth interviews.
- Part 3: Analyzing in-depth interviews: Unveiling insights from conversations.
Together, the series provides a practical and methodological foundation for designing, conducting, and analyzing in-depth interviews and translating qualitative evidence into defensible research insights.
