In the field of qualitative studies, the one-on-one interview is the most commonly used technique because it's the simplest to put into practice. One-on-one interviews are especially useful for preparing a survey, understanding the results of a survey or experiment, identifying what motivates or prevents someone from consuming a product, and determining the criteria for choosing to buy a certain product. You’ve guessed itthe goal of this approach is to get to know your customers better!

Whether you’re a student, marketer, or researcher, read on for advice on conducting (or ordering) one-on-one interviews and taking advantage of everything they have to offer over other qualitative study methods.


One-on-one interviews ensure the subject's responses remain free and spontaneous, in contrast to what can happen in focus groups, where the atmosphere is somewhat intimidating. The information is therefore not influenced by the leader effect, copying behaviour, or psychological pressure. The flexible structure of the conversation also allows for very personalised prompts, which are especially useful for developing valuable customer typologies and confirming an existing concept.

Nevertheless, one disadvantage associated with this method is its considerable lag time. In general, it takes several weeks of analysis to obtain usable results. This method requires thorough preparation prior to the interview, the use of an experienced professional, an in-depth analysis of the results, and sometimes a significant budget.


A “good” one-on-one interview usually lasts 45 to 90 minutes. Of course, it’s always best to conduct this kind of interview face to face. However, if that isn’t possible, or in certain special cases, you can do the interview over the phone.

Your sample size will be small because each interview contains a large amount of information. However, your sample should be rather heterogeneous. To make sure that it is, you can use a technique known as maximum diversity sampling. The purpose of this approach is to seek a wide range of respondent profiles as defined by two to three criteria. How many people should you interview? Generally, you should interview ten to twenty people, stopping as soon as additional interviews no longer provide new information. Keep in mind that extrapolating the results to the entire population is practically impossible.

One-on-one interviews are conducted with an interview guide. This written document summarises the main topics the interview will be based on. Make sure you don’t confuse it with the survey. The guide’s level of detail varies depending on the type of interview you're conducting.

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One on one interviews is a good way to understand better customers


There are three types of interviews: 

  • Structured interview: the interview guide is very detailed and includes topics as well as sub-topics. Before finishing the interview, the interviewer must check that each topic has been discussed.
  • Semi-structured interview: the interview guide is much less detailed, and if the subject does not bring up all the topics, the interviewer does not force the topic unless it’s a main one.
  • Undirected interview: the interviewer simply asks a main prompt (topic) at the beginning of the interview and nothing else. The interview guide changes over time.

Before the interview, you should create an interview guide, schedule an appointment with the respondent, and prepare your recording equipment. Every interview should be recorded. It’s best to use a microphone. The entire interview is recorded so a complete transcript can be made from the subject’s responses.


You're ready for the moment of truth—the one-on-one interview. Start by explaining the purpose of the study and how the interview will be conducted. Next, move on to the “purging phase.” This part consists of assuaging all the respondent’s fears. The goal is to put the person at ease. After this step, you can start your structured, semi-structured, or undirected interview.

You almost never need to interject anything during the interview. Simply bring up each topic. The goal is for the respondent to talk about the maximum number of topics listed in the guide as possible without outside help. You should remain neutral and objective and must never express your personal opinions. Using reformulation techniques is the only way the interviewer can interject something during the interview.

  • Follow-up reformulation: (“And then?”, ”But?” ).
  • Confirmation reformulation: (“If I've understood correctly...”).
  • Investigation reformulation: (“Could you explain that again?”).

These techniques make it seem like you're having a conversation, but in no circumstance should the interview actually turn into one. Don’t ask any leading or close-ended questions. In addition to the recording, the interviewer should take quick notes to be able to build on an idea and not lose any information.

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The quality of the data collected depends strongly on the involvement and experience of the person conducting the one-on-one marketing interview, whether he or she is a researcher, a psycho-sociologist, or another type of professional. The interviewer must be adept at listening actively and according positive attention to the subject while also correctly using the reformulation techniques. His or her goal should be not to tell, but to make the interviewee speak in order to produce a sincere, realistic, and unbiased statement. Other key interviewing skills include managing instances when the subject falls silent or pauses to think as well as understanding non-verbal cues.

All the interviews must be transcribed in order to be analysed. Make sure to include every word the subject said in the transcription! The analysis should be based not just on note-taking, but also on the recording and transcription of the conversation. That way, you can be sure to have the facts and a detailed rendering of the ideas. Verbatim accounts should be written in complete sentences so you can better understand their context. This is a long but, unfortunately, necessary process. Next, the researcher analyses the content using the verbatim accounts, or excerpts from the respondents' commentary. He or she creates lists of words, topics, verbs, etc. and organises the information by topic or by respondent profile.

The one-on-one interview serves as a complement to the focus group and offers an interesting analytical methodology for collecting qualitative data about the purchasing experience and for better understanding what motivates consumers. It can also be used to supplement other techniques for collecting verbatim accounts. 

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