Mastering Interview Techniques in Research: Concepts and Categories

Every researcher studying human behaviour faces a fundamental question: how do you get people to tell you what they actually think, feel, and experience? The answer, more often than not, is the interview. Described as a purposive conversation – a deliberate, goal-directed exchange between a researcher and a respondent – the interview is the most widely used qualitative data-gathering technique in the social sciences. According to Deakin University’s qualitative research guidelines, interviews are used across grounded theory, case studies, and focus groups precisely because they allow researchers to access something no survey tick-box ever can: the meaning people attach to their own experiences. But not all interviews work the same way. Choosing the right type is as important as asking the right questions.

What makes an interview a research tool? 🔗

At its most basic, an interview is a question-and-answer exchange – something all of us do every day. But a research interview is a very specific kind of conversation. As Nature Reviews Methods Primers notes, interviews in social science research are guided by the researcher and used for specific analytical ends, which immediately sets them apart from casual conversation. They are designed to uncover how people understand and interpret the world around them – their attitudes, beliefs, motivations, and lived experiences.

Unlike a questionnaire that captures surface-level answers, a research interview is designed to go deeper. According to Sociology Institute, interviews are especially powerful when the research question is exploratory, sensitive, or layered in social complexity. They can run from thirty minutes to several hours, and they can be conducted face to face, over the phone, or via video platforms – each mode carrying its own methodological implications.

Broadly, research interviews are classified by their level of structure – the degree to which the questions, their order, and the expected responses are predetermined. Three primary formats exist: unstructured (informal), structured, and semi-structured. Beyond these, focus group discussions represent a distinct but closely related category that deserves separate consideration.

Informal (unstructured) interviews: conversation as data 🔗

The informal interview – also called the unstructured interview – is the most open-ended format available to a researcher. There is no fixed questionnaire, no predetermined order of questions, and no set range of responses. Instead, the researcher has a broad topic or set of themes in mind, and allows the conversation to develop naturally from there.

According to a study published in the Journal of Basic and Clinical Pharmacy, unstructured interviews resemble a conversation more than a formal interview, and are often described as a “controlled conversation” – one skewed toward the researcher’s interests, but not bound by a rigid script. Within this category, the non-directive interview aims to gather in-depth information without pre-planned questions, while the informal conversational interview generates questions spontaneously during the session itself.

This format is particularly well-suited to exploratory research, where the researcher is investigating new territory and lacks a robust theoretical framework to guide structured questioning. ATLAS.ti’s research guide notes that unstructured interviews are ideal for sensitive subject areas – studies of hospice care, migrant work, or personal trauma, for instance – where a structured approach might cause participants to shut down rather than open up. The goal is to build rapport and allow the respondent to guide the narrative on their own terms.

The trade-off is reliability. Because every informal interview unfolds differently, comparing responses across participants is difficult. The data is rich but rarely systematic, which makes analysis time-intensive. For researchers who are experienced enough to manage an open-ended conversation without losing sight of their research objectives, however, this format can yield insights no structured questionnaire could produce.

Structured interviews: precision and scale 🔗

At the opposite end of the spectrum sits the structured interview – a format where questions are predetermined, asked in a fixed order, and often offer a limited set of response options. Scribbr’s research methods guide describes structured interviews as a predominantly quantitative tool: their closed-ended, standardised nature makes it easy to spot patterns across large samples and compare responses between participants while keeping other variables constant.

This is the format of choice when a researcher needs scale. If the goal is to understand how an entire population feels about a media policy, a public health measure, or a social trend, structured interviews allow data collection from hundreds or thousands of respondents in a consistent, replicable way. QuestionPro describes the structured interview as a “standardized interview,” noting that its rigidity is precisely what ensures reliability – different interviewers asking the same questions in the same way to different respondents produces data that can be aggregated and statistically analysed.

Telephonic interviews 🔗

One of the most established delivery methods for structured interviews is the telephone. Research published in PMC confirms that the telephone interview is an accepted and well-studied approach for quantitative data collection and remains one of the most widely used survey methods in many countries. Telephone interviews allow researchers to reach geographically dispersed populations without the logistical and financial costs of face-to-face fieldwork. In many research settings, this is done using Computer-Assisted Telephone Interviewing (CATI), where an interviewer reads from a script displayed on a screen and inputs responses directly into a database.

One notable feature of the telephonic format is the absence of visual contact. While this can limit a researcher’s ability to read non-verbal cues, studies suggest that some participants actually feel more comfortable disclosing sensitive information over the phone precisely because they are not in the interviewer’s physical presence. The challenge lies in maintaining rapport and keeping respondents engaged without the anchoring effect of face-to-face interaction.

Online surveys and web-based structured interviews 🔗

Digital technology has added a third major channel to structured interviewing: online surveys and web-based interview platforms. These instruments allow researchers to reach massive samples at a fraction of the cost of in-person or telephone interviews. Self-administered online questionnaires, structured video interviews, and hybrid tools that combine branching question logic with live interviewer interaction all fall within this category.

The Harvard Library’s qualitative research guide references the growing importance of internet-based surveys in social science research, noting that digital tools now offer capabilities – interactivity, the presentation of visual stimuli, and real-time branching – that were simply not available in earlier modes of structured data collection. The key limitation remains: structured interviews, regardless of delivery mode, are better at capturing what people think than why they think it.

Semi-structured interviews: depth within a framework 🔗

The semi-structured interview occupies the middle ground – and it is by far the most commonly used format in qualitative social science research. Oregon State University’s open qualitative research textbook describes it as the “primary form of interviewing used by qualitative researchers in the social sciences,” sometimes referred to as an in-depth interview.

In a semi-structured interview, the researcher prepares an interview guide – typically five to ten questions or topic areas – in advance. The guide ensures that the same core themes are addressed across all participants, providing a degree of comparability. But unlike a structured interview, the guide is not a rigid script. The researcher can adjust the phrasing of questions, change their order, and introduce follow-up probes based on what the respondent says.

This flexibility is what gives semi-structured interviews their power. As noted in peer-reviewed research on qualitative interviewing, semi-structured interviews are based on preset open-ended questions, and the interviewer is free to pursue clarification or deeper exploration when the respondent raises something unexpected or significant. The result is data that is both systematic enough to compare across participants and rich enough to capture nuance, contradiction, and complexity.

The format does demand skill. The interviewer must keep the conversation moving productively, ensure all key topics are covered, and resist the temptation to steer respondents toward expected answers. But when executed well, semi-structured interviews offer what neither pure structure nor pure informality can achieve alone: guided discovery.

Focus group discussions: interviews in a social setting 🔗

A focus group discussion (FGD) is a distinct method that brings elements of the interview into a group setting. According to Wikipedia’s documented research on focus groups, a focus group involves a small number of demographically predefined participants – typically between six and twelve – who are asked about their attitudes, perceptions, and views on a given topic, guided by a trained moderator.

Focus groups originated in the early 1940s and were notably used to explore morale among American troops during the Second World War. Research published in PMC notes they have since become widely used in health care, needs assessment, market research, and social science. The core value of a focus group lies in its interactivity – participants do not just respond to the moderator, they respond to each other. This “piggybacking” effect, where one participant’s comment sparks or deepens another’s, can surface perspectives and vocabulary that individual interviews might never reveal.

Focus groups are particularly effective for understanding how meanings and opinions are formed socially – not just held individually. The University of Surrey’s Social Research Update identifies a key advantage: focus groups are especially suited for obtaining multiple perspectives on the same topic, and when participants feel involved in something meaningful, the setting can be genuinely empowering.

However, the group setting also introduces specific risks. Research Design Review highlights the risk of groupthink – participants may suppress minority views and align with the prevailing mood of the group. Dominant personalities can steer discussions in ways that marginalise quieter voices. Sensitive personal topics may go undisclosed in a group setting where confidentiality cannot be fully guaranteed. And the quality of data is heavily dependent on the skill of the moderator – a poorly facilitated group can produce data that reflects the dynamics of the room rather than the genuine views of its participants.

Choosing the right interview type 🔗

There is no universally superior interview format. The right choice depends on the research question, the target population, the depth of understanding required, and the resources available. Harvard Library’s research guide makes the point clearly: the decision to use a particular interview type should flow from the methodological paradigm of the study – whether it is interpretive, critical, positivist, or participatory in orientation.

As a practical guide: informal interviews work best when a researcher is entering unknown territory and needs to let the respondent lead. Structured interviews – telephonic or online – are the right tool when scale, standardisation, and quantifiable outputs matter most. Semi-structured interviews are the default for most qualitative social science work, offering the combination of comparability and depth that most research questions require. And focus group discussions are most valuable when the research question is about shared meaning, group attitudes, or the social construction of opinion – not individual narratives.

Knowing these distinctions is not just academic. It shapes every decision that follows: how questions are written, how participants are recruited, how data is recorded and analysed, and ultimately, what kind of knowledge the research can claim to produce.

What do you think? Given that each interview format serves a different research purpose, how should a researcher decide between a semi-structured interview and a focus group discussion when studying a sensitive social issue? And as online and telephonic interviews become more common, do you think anything essential about the research relationship is lost when the interview is no longer face to face?

References

1. https://deakin.libguides.com/qualitative-study-designs/interviews
2. https://www.nature.com/articles/s43586-022-00150-6
3. https://sociology.institute/research-methodologies-methods/interviewing-types-techniques-field-research/
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC4194943/
5. https://atlasti.com/guides/interview-analysis-guide/formats-types-of-interviews-research
6. https://www.scribbr.com/methodology/interviews-research/
7. https://www.questionpro.com/blog/types-of-interviews/
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC3238794/
9. https://guides.library.harvard.edu/c.php?g=796889&p=10476198
10. https://open.oregonstate.education/qualresearchmethods/chapter/chapter-11-interviewing/
11. https://en.wikipedia.org/wiki/Focus_group
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC2642503/
13. https://sru.soc.surrey.ac.uk/SRU19.html
14. https://researchdesignreview.com/2020/11/10/limitations-focus-group-method-an-overview/