The following blog post was written by Sara Cruz, Research Analyst at RMS.

An in-depth interview (IDI) is a type of qualitative research. It involves an interview, often with just a single respondent and is conducted by a trained interviewer. The purpose of an in-depth interview is to understand thoughts, feelings, perceptions, beliefs, attitudes, or motivations related to a specific subject. IDIs typically last from 15–45 minutes and can be conducted in-person, over the phone or virtually as a video conference.

IDIs can be used for a variety of research including branding research, customer satisfaction, new product/service interest, and customer insights. The qualitative results from an IDI project provide valuable insight to guide next steps for a company or organization.

IDI projects have many similarities to other market research methods, but there are some important and beneficial differences as well.

 Here are 4 Key Benefits of IDIs:

#1 Richness of data

Interviewees provide expansive detail with responses in comparison to an online survey. IDIs are typically semi-structured, with more open-ended questions than you’d seen in an online survey. These open-ended questions prompt the interviewee to openly share instead of choosing from a list of provided options.

#2 Real-time

An IDI is conducted in real-time. Unlike an online survey, it is conversational by nature. This creates a dynamic where interviewees are comfortable and willing to share their thoughts and feelings on a topic.

#3 Ability to probe

A highly skilled interviewer has the experience to know when to “go off-script.” Unlike an online survey where the respondent answers one question and moves on, the interviewer can probe deeper after a response. For example, “Can you please share with me more about what you mean by ___________?” Or, “I heard you mention X, can you tell me more about that?”

#4 Smaller sample size

There is no “right” number of IDIs to conduct for a project. At RMS we recommend at least 12. IDIs require a smaller sample size compared to an online survey. Since the data is qualitative, common themes arise quickly with a smaller sample.

IDIs are a valuable qualitative market research tool. If you are wondering how an IDI can help you with your market research needs, reach out to us.

RMS is a professional market research firm that can help you successfully navigate these changing times. If you are interested in learning more about our research capabilities, please contact Sandy Baker, Vice President of Corporate Development, at or by calling 1-866-567-5422.