What types of interviews are there?

You have decided that interviews are an appropriate research method for your thesis. But then, the next question arises: what type of interview do you choose? Do you organise a focus group with several people together? Do you opt for a structured or semi-structured interview? Or, is another interview format more appropriate? This explanation of the types of interviews will help you make this choice.

The first type of interview is a structured interview. This means that you follow a set question structure during the interview. You have determined the questions and their order in advance, and do not deviate from it. 

This strict form of interviewing can be useful if you want to interview the entire sample in the same way, keeping each interview as similar as possible. By doing so, you increase the reliability and validity of your results. This ensures that your results are not influenced by the method of questioning; after all, everyone was asked the same questions in the same way.

Structured interviews are common in quantitative research. In this type of research, you usually see closed questions. By interviewing each participant in exactly the same way, you can aggregate the answers and analyse them statistically. This interview form can also sometimes be appropriate for qualitative research. However, it is not an appropriate interview method if you want to explore a particular topic in depth.

In a semi-structured interview, you have more freedom regarding how you conduct the interview. However, you still make an interview guideline beforehand. This outlines, for instance, what kind of questions you want to ask. During the interview, you keep some room to deviate from your guide, and to ask further questions or for an explanation when necessary. 

A semi-structured interview is also known as an in-depth interview. This is because it is a good type of interview for collecting detailed information. This makes it an appropriate imethod for qualitative research.

A slightly different form of an in-depth interview is an unstructured interview. In this version, you don't have any questions prepared at all. Instead, you only have a topic list at hand. This lists the topics you want to cover in the interview. You determine the questions in real timeduring the interview based on what the other person says.

This kind of interview gives you a lot of freedom to pick up on interesting things. The downside, however, is that you have to improvise a lot. Some interviewing experience is therefore useful before conducting this type of interview.

A focus group is slightly different from the other types of interviews. A focus group involves a group of people (often 8 to 10 people) discussing a specific topic together. As the researcher, you ask general questions and facilitate the discussion. In doing so, you allow the participants to interact. Interesting insights often emerge from the conversations between participants. 

In terms of structure, a focus group is most similar to a semi-structured interview. You already have the questions set, but mainly wait to see what spontaneously develops during the conversation.

Instead of a focus group, you can also organise a group interview. This works a little differently. The focus group focuses on people talking to each other about one topic. In a group interview, the interaction between participants is less important. You ask questions to the group as a whole and wait to see who answers. Also, a group interview usually involves the exploration of several topics.

In practice, of these different types of interviews, semi-structured interviews are the most common. It is useful to have the ability to respond to what the person says. At the same time, you have the structure of a questionnaire. The fact that you can ask more questions helps you find out more about the research subject that you may not have expected beforehand. 

In some types of research, a structured interview is most useful. This is true in quantitative research where each participant must be interviewed in exactly the same way. Reliability and validity are lower in a semi-structured or unstructured interview than in a structured interview. 

A successful interview depends on having good interview questions. That is why we would like to give you some guidelines for developing strong interview questions, and what interview questions should look like. Also, take a look at our step-by-step plan for conducting interviews. It will help you keep the interviews on the right track, from start to finish.