The in-depth interview is a data-collection method that many qualitative researchers reach for when researching questions that a group setting cannot deliver. The method seems ‘easily doable’ because the basic mechanics are familiar: ask questions, listen, and probe. But there is a significant difference between a session that simply collects responses and a session that generates valuable insights, and that difference comes down to the preparation that precedes the interviews and the moderation skills applied.
What the IDI is actually doing that other methods cannot
Before getting into the process, it is worth being precise about what the in-depth interview is specifically designed to deliver.
In an online focus group, the interaction between participants is what perhaps delivers most value to the researcher - people challenge one another, build on each other's ideas, and bring to the table the shared language of a category, in ways that no individual-based data-collection method can replicate
But that same dynamic is exactly why a focus group is the wrong method, the moment the research question requires individual-level reasoning. In an in-depth interview, there is no audience to perform for, no social contract to maintain, and no group consensus pulling responses toward the centre.
This difference is what makes IDI research the right choice for studies involving:
Sensitive topics, where social desirability effects would distort a group setting
Senior B2B decision-makers, whose schedules might be harder to coordinate to bring them in a group and who might hesitate to express their real reasoning in a group context
Journey mapping, which requires the full arc of an individual's experience (not a group-level summary of it)
Broadly speaking, there are 3 formats that in-depth interviews can take:
Structured interviews, which apply a fixed question set in a fixed order, with standardised wording. Some refer to this method as ‘Qual-at-scale’ interviews. Every participant is asked the same thing, the same way. The benefit is comparability across a large sample. The cost is that there are no organically generated threads of discussion when conducting the interview. Which means the moderation is limited to the exact questions stated in the discussion guide. Structured interviews are best leveraged when consistency across a high volume of sessions is the priority.
Semi-structured interviews are possibly the format that most commercial qualitative research runs on. The moderator enters with a pre-prepared guide, which addresses the key research questions. Yet, the moderator has full freedom to probe, reorder sections, probe beyond questions mentioned in the discussion guide, and pursue threads that emerge from participant responses. Here, the discussion guide works as a framework, rather than a script to be tightly followed.
Unstructured interviews, which typically open with one or more broad topics, then follow the participant entirely. In experienced hands, they can produce extraordinarily rich data. Such interviews work where the research questions are not tied down to a specific brand/ category/ communication. For instance, a study meant to uncover and understand Gen Z values could start with the moderator asking an innocuous question - “So what does your typical weekday look like?” - then pursuing several conversation threads, based on participant responses.
All “good” IDIs start with great prep work.
There is a persistent assumption in qualitative research that data quality is primarily a function of moderation skill. Sure, moderation skills matter. However, IDIs can be designed to produce quality data much before a moderator starts conducting a session.
To begin with, data quality is a function of how clearly the research questions have been coined by the client and communicated to the research team.
For instance, a research question like "What are consumer attitudes to healthier eating today?" is merely a territory masquerading as a research question.
Instead, a question that can actually drive an in-depth interview study’s success could be: "Why do consumers who consistently describe Health as a personal priority choose not-so-healthy options at the point of purchase?" That level of specificity shapes every section of the guide, every probe, and every analysis-related decision made after the transcripts come in.Next, clients, researchers and moderators need to agree that the discussion guide is a map, not a script. It is meant to be used to balance coverage of multiple research questions; rather than being an exhaustive list of questions that could have been a Quantitative questionnaire.
A well-built discussion guide for a 60-minute semi-structured interview is structured in sections, with each section covering a single information area.
For instance, here’s a realistic guide structure for a 60-minute, category U&A IDI:
Running the session
Know that the first five minutes of an in-depth interview are where the conditions for honest data are either established or missed, and once missed, they are very difficult to recover mid-session.
A strong opening does three things: it explains the broad purpose of the research without signalling what answers are being looked for; it explicitly tells the participant that there are no right or wrong responses and that contradictions and uncertainty are as useful as clear opinions; and it uses warm-up questions to help build the moderator-participant rapport.
The way a participant answers a low-stakes opening question tells a moderator more about how to listen to them for the rest of the session.
Are they naturally eloquent and expressive, or do they need drawing out?
Do they think in abstractions or in specific examples?
Do they tend to qualify everything, or do they express their views as black or white?
All of this understanding helps shape moderator probes in the next 50 minutes.
Remember that Probing is what unearths relevant, rich, usable data-points
The first answer to any question is almost always the surface version. Cognitively available, socially acceptable responses are easiest to put forth.
However, the data that actually moves things for analysts and researchers lives in the second and third layer underneath, and the only route there is the probe.
Probing questions that open issues up, rather than bias participant responses:
"Can you tell me more about that?" is an underrated probe in the qualitative toolkit. It’s simple, neutral, and almost always serves the purpose.
"What do you mean when you say [participant's exact word]?" Reflecting back on their language helps nudge them to think of more mainstream language, which often uncovers what they want to actually express.
"Can you think of a specific time when that happened?" This moves a participant from an abstract comment to concrete experience, enabling specific, quotable, analytical data to surface.
"What would have to be different for that to change?" Forces the participant to articulate the conditions behind their opinion, rather than just restating the opinion in different words.
"You mentioned X earlier, and just now you said Y. How do those two sit together for you?" Participants who hold contradictory views are not confused. They are simply revealing the genuine complexity of their opinion on the topic, which is precisely what qualitative research exists to capture.
Treat a discussion guide as a quality control mechanism, not a constraint. It ensures the key information areas get covered, while giving the moderator a structure to return to when a session drifts.
When a participant opens a thread worth probing that belongs to a later section of the guide, the right call is almost always to follow it. When a section is producing nothing new after two or three exchanges, compressing it and moving on wastes less of the session than pushing through it, out of a ‘sense of duty’ to the document.
Moderators who produce the richest IDI data are the ones who understand what the guide is trying to achieve well enough to discerningly stray from it, where required.
Closing a session can be as critical as its start.
The logistical close of an IDI, confirming next steps, thanking the participant, and explaining incentive timing is quite straightforward. What often gets skipped is the substantive close: "Is there anything you expected me to ask that I did not?"
Responses to this question often produce valuable data, because it is entirely unprompted and participant-generated. What they raise in response to that question is what they genuinely felt was missing, and it is relevant enough to capture.
Recognise that participants experience
Online in-depth interviews differently, as compared to in-person interviews. The most consistent gap in online in-depth interviews is the observer environment. When a client or stakeholder is visible or audible to the participant, the data becomes vulnerable to contamination and bias. Participants who sense they are being evaluated by more than one person might adjust their responses accordingly, usually toward more considered, socially acceptable, less spontaneous answers.
The bottom line
The in-depth interview is a data-collection format that gets closest to understanding human reasoning from the individual’s standpoint.
Even experienced researchers could make certain mistakes that dilute the data quality they can fetch from in-depth interviews:
Accepting the first answer. The surface response is not the finding. Probe once, and then probe again.
Following the guide out of obligation. A section that is producing nothing new after three exchanges is not going to start producing something useful in the fourth. Recognising when to compress and move on is also a skill worth mastering.
Confusing an interview with a conversation. A well-run, in-depth interview feels like a conversation; yet it follows an analysis framework and addresses specific research questions.
FAQs
What is an in-depth interview in qualitative research?
A one-to-one moderated conversation of 45 to 90 minutes designed to explore individual motivation, experience, and attitude in depth, without the social dynamics of a group setting.
What is the difference between a structured and semi-structured interview?
A structured interview follows fixed questions in a fixed order; a semi-structured interview uses a guide as a framework but gives the moderator freedom to probe and follow relevant information threads.
What makes a good discussion guide for an IDI?
Sections rather than question lists, open-ended questions that cannot be answered yes or no, probes built into each section, and a length that is realistic for the available session time.
How do you probe effectively without leading the participant?
Reflect back the participant's own words, ask for a specific example, pursue apparent contradictions, and use silence before introducing a new question.
Can in-depth interviews be conducted online?
Yes, and the majority in 2026 are; the method does not change, but the environmental requirements do, including a separate observer room and a platform built for research rather than general video calls.
Ayushi Jain
(Content Writer)
She is a content writer specializing in the intersection of human inquiry and modern efficiency. Through her work at flowres.io, she explores how qualitative research is evolving and highlights the tools that help researchers maintain their creative flow.
Posted on: Jun 22, 2026
