A depth interview (often referred to as an “in-depth interview“) is a specific style of one-to-one interview used in qualitative research. The primary goal of a depth interview is to dig beneath the surface of a person's thoughts and experiences, uncovering their beliefs, opinions, values, and motivations. In this article, we’ll take a look at how depth interviews are different from other research methods, what the research process looks like, and which industries use depth interviews to learn more about the people they serve.

How Are Depth Interviews Different from Other Research Methods?

At first glance, depth interviews might seem similar to other research methods and interview styles. After all, they still involve asking people questions about their lives and opinions. However, depth interviews go beyond surface-level opinions and personal facts. Here’s a quick look at how depth interviews compare to two other forms of qualitative research.

How Depth Interviews Compare to Other Qualitative Research Methods
	Depth Interviews	Focus Groups	Surveys
Purpose	To explore why people think, feel, and act in a certain way.	Designed to gather group opinions and reactions to products, ideas, or concepts; particularly useful for observing group dynamics and shared perceptions.	To collect views and detailed data from a larger population. The goal is to measure trends, preferences, or behaviors using structured questions that can be analyzed statistically.
Sample Size	Typically a small, carefully chosen group of research participants.	Small to medium groups (6–10 participants).	Large sample sizes, often hundreds or thousands of respondents.
Structure	Usually semi-structured, guided by an interview guide or discussion guide, but flexible enough to follow the participant’s lead.	Moderated discussion following a set of key topics, but participants may influence each other’s opinions.	Highly structured with fixed questions. Often includes a mix of open-ended and closed-ended questions to gather personal insights and quantifiable data at the same time.
Data Collected	Rich, descriptive qualitative data, including non-verbal cues, body language, and the participant’s thoughts in their own words.	Shared verbal feedback and group interaction data.	A mix of numeric data and descriptive qualitative data.
Time Commitment	Time-consuming; each interview can take 30–90 minutes plus transcription and analysis.	Moderately time-consuming, sessions last about 1-2 hours plus transcription and analysis.	Relatively quick to conduct and analyze once all responses are collected.

 

Why Depth Interviews Matter in Qualitative Research

In qualitative research, depth interviews stand out as one of the most effective methods for uncovering the why behind human behavior, which can be very difficult to capture with other research methods. And because depth interviews are one-to-one, participants often feel more comfortable sharing information about themselves that they might not be comfortable expressing in a group setting or written survey. This makes depth interviews especially valuable for delving deeper into more sensitive and complicated topics. Which Industries Use Depth Interviews? Lots of different industries use depth interviews to learn more about their customers, employees, and the broader public. Here are just a few examples.

• Market Research - To uncover how customers really feel about products, brands, and services.
• UX and Design - To understand user needs, frustrations, and behaviors when using products.
• Healthcare - To gain valuable insights into patient journeys and barriers to care.
• Human Resources - To explore themes related to employee engagement, workplace culture, and leadership.
• Politics - To understand voter attitudes, beliefs, and opinions.

Depth Interviews in Action: A Step-by-Step Guide

Conducting in-depth interviews requires careful preparation and, most importantly, emotional intelligence. Read on for a step-by-step guide on the in-depth interview process.

1. Define Your Research Question and Goals

   Start by getting crystal clear on what you want to learn. A focused goal helps shape better questions, and ultimately, better insights.

2. Recruit the Right Participants

   Choose a small number of participants (3-5) who genuinely represent the population you’re looking to learn about, but who are also different enough to provide unique perspectives.

3. Develop an Interview Guide

   Create an interview guide with open-ended questions. Your guide will serve as your roadmap (not a script) that you can adapt as you go.

4. Prepare Your Setup

   Choose a quiet, private location where participants feel relaxed. Test your recording equipment, prepare note-taking materials, and minimize distractions so the conversation can flow naturally.

5. Build Rapport and Trust

   During your interview, make sure to engage in small talk and thank participants for their time. This will help participants feel comfortable opening up to you.

6. Practice Active Listening During the Interview

   Try to listen more than you talk, and always ask follow-up questions that make sense with each response. You should also be sensitive to changes in tone and body language, and adjust questioning accordingly.

7. Record Detailed Notes and Observations

   In addition to recording the interview, take notes on any non-verbal cues and emotions in responses. These small details will come in handy during the analysis phase.

8. Conduct Follow-Ups if Needed

   After reviewing your notes and transcripts, you might notice some gaps in your participants’ stories. If this happens, it’s worth having a follow-up conversation or phone call to clarify any specific events or details.

9. Analyze the Data Collected

   Once everything’s recorded and transcribed, you can then analyze your findings and look for themes, patterns, and insights worth sharing in your final research report.

Key Advantages and Disadvantages of Depth Interviews

Like any research method, depth interviews come with some strengths and challenges. Here are the main advantages and disadvantages to be aware of.

Depth Interviews: Advantages and Disadvantages
Advantages	Disadvantages
Because participants respond in their own words, you can rely on the qualitative data collected as accurate and grounded in real human experiences.	Compared to other research methods, in-depth interviews can be time-consuming to prepare, conduct, and analyze.
The semi-structured format allows interviewers to adjust questioning and uncover richer, more detailed insights.	In-depth interviews only use a small sample size, so findings can’t necessarily be generalized for larger populations.
Researchers can directly observe body language and pick up on non-verbal cues, which is useful for analysis and drawing conclusions.	Since interviews are not standardized, differences in the interviewer’s tone and phrasing may influence participants’ responses.

 

Final Thoughts

When done well, depth interviews allow researchers to see the world through someone else’s eyes. Yes, they can take some time and patience to conduct. But the insights they reveal can inspire better products and more practical, human-centered services.

Frequently Asked Questions About Depth Interviews

1. When are in-depth interviews used?

   In-depth interviews are used when researchers want to explore sensitive or complex issues that can’t be captured with a basic survey or structured interview. They are often used in market research, UX, organizational research, and healthcare.

2. What are the main drawbacks of depth interviews?

   Depth interviews are time-consuming, difficult to generalize, and highly dependent on the interviewer’s skill. This is why they’re often used during the exploratory phase of research, where the goal is to uncover nuanced insights and underlying motivations.