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In-depth Interview (IDI)

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In-depth interviews are one-on-one conversations with users about their experiences with a product, service, or website. Conducting them can help you better understand users, the background of their decisions, and why they do something. This information helps to improve your product or service based on their feedback. Let’s check out this in-depth interview guide to learn why and how to organize this research method.


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In-depth interviews (IDI) are a significant part of every UX research and design process. They are a great way to help you get to know your users better, learn about their problems, gains, and discover their needs and wants. It is a form of qualitative research that focuses on a singular user to talk with them honestly about their feelings, goals, frustrations, and motivations.

Answers collected from this kind of research deepen the knowledge about user behavior and expectations, giving us more detailed perspectives from a user about already existing products or designing new experiences.

In-depth interviews are also a great way to gather the information that will help uncover potential usability issues with your product or service. For example, if you're working on a software app, an in-depth interview will help you understand what kinds of tasks people need to perform with the app, how they currently solve those problems, and what solutions we can propose ourselves.

In-depth interviews are one of the most valuable parts of user research because they can reveal insights that can't be achieved through other methods. This UI and UX research method involves conducting multiple individual interviews. They usually take the form of one-on-one meetings with one interviewee and one moderator.

In some cases, it is possible to meet with two (dyads) or three (triads) respondents that complement each other with their experiences or have contradictory opinions.

Having more than one participant helps the researcher to stimulate more activity in the respondents, engage them more, and sometimes encourage them to talk in the presence of a familiar person. It is a common technique that note-takers also take part in IDI to write down the most important insights and reflections.

However it is important to remember about the risk of those kinds of interviews, where a person can influence the answer of another person. Still, it can be a useful tool when, for instance, we want to know more about a student and we interview both parents – or similar to when a wedding planner meets with a couple to talk about the marriage and wedding decisions.

IDI can be conducted face-to-face or remotely. Nowadays, especially in and after the pandemic, when many people moved their lives and work to an online environment, it became more popular to conduct interviews remotely. However, face-to-face meetings still have some advantages and are used because they don't exclude non-tech savvy individuals. It can also help to observe more non-verbal signals from respondents during the interview that may explain a lot of users' feelings.

At Dodonut, we prefer and promote remote, online interviews, which have several advantages.

Firstly, they resonate with our sustainable approach - we don't generate CO2 through commuting and traveling to respondents.

Instead we use online tools, like Google Meet, Microsoft Teams, Miro, and Figma, to organize interviews and collect insights. Moreover, remote interviews can positively impact the respondents' comfort.

They can choose the space in which they feel comfortable, they can speak while sitting on their coach, and it is easier to find the perfect time for this online interview, even in the evening, when somebody is relaxed after work.

As in-depth interviews represent qualitative research methods, it is not easy to analyze them and recognize repeated patterns that you can use to represent statistics. When you need quantified results, you can use other quantitative research methods like surveys, web analytics, eye-tracking, or A/B testing.

Because in-depth interviews are more flexible in structure than moderated usability studies, they are helpful in situations where you may want to ask participants the same or similar questions but also want to explore the responses in greater depth.

To visualize the difference between an in-depth interview (quantitative research) and a survey (qualitative research), let's imagine a group of people who use an app that counts calories, records activities, and recommends recipes.

Surveys with quantitative questionnaires will include a large group of users that would be asked to answer a list of closed-ended question and ready list of answers, for instance:

  • How often do users weigh themselves?
  • What features do users like most about your product?
  • How much time do they spend daily recording their training and eating food?

But, suppose we would like to tailor more questions for a more personal view to get more detailed answers about user feelings, experiences, and behaviors. In that case, we should conduct in-depth interviews with a chosen, narrowed-down group of people in a form of one-on-one meeting. During such an interview, it would be best to ask opened-ended questions about:

  • What motivates the user to lose weight?
  • What frustrates the user in the current chosen diet plan?
  • How do users feel when they see progress in a dietary plan or see no effect?

We use in-depth interviews to gather insights, usually when we want to implement a new feature, but we don't know what it should look like. Or when we want to create a customer journey better to understand the touchpoints and pain points of the user.

Then, quantitative research serves us to confirm what we learned from the qualitative research phase. To sum up, quantitative methods help to answer what users do, and qualitative research gives us the answer to why they do it.

Both types of research methods, qualitative (surveys) and quantitative (IDI) techniques can be effective when we combine them to get the most valuable insights that can help design the best user experience.

In such an interview, all questions, their order, and even some answers are imposed in advance. The interviewer has very carefully written instructions with a list of questions and how to code the respondent's answers. It does not allow for exploring the topic or contacting spontaneously with the respondent and is limited to verifying the assumptions.

In semi-structured interviews, the moderator has a set of questions. Still, they can modify them and ask them in a different order, for example, when the conversation turns naturally into new tracks. In such a conversation, there will be room for both open-ended and closed-ended questions and projection techniques. In the semi-structured interview, as in the casual discussion, the researcher can inquire and formulate additional questions not previously provided for in the scenario, which allows for a deeper understanding of the problem.

Due to the exploratory nature of research problems, it is worth conducting semi-structured interviews with many open questions and giving a lot of freedom to experienced researchers.

In casual interviews, the moderator only has the thematic scope given, but in the conversation, they independently formulate questions and determines their order. Such discussions are based mainly on building a relationship with the respondent, thanks to which it is possible to reach even sensitive information. Casual interviews are conducted when the exploration of phenomena is more critical than verifying hypotheses or when there are simply no hypotheses. It can be performed only with experienced researchers who always remember examined study areas.

In-depth interviews are one of the most effective ways for companies to connect with their customers and hear what they think about their products or services. If you have any doubts about conducting an IDI yourself, think about several reasons why it is a good idea to conduct qualitative interviews:

  • When you want to launch a new product or service, you want to get some ideas, reflections, and insights for potential customers.
  • When you already have a product but want to revise how it works with users, what do they think about it, what problem they notice, and what would be their needs and expectations about it. Answers can serve later to redesign the product to provide a well-suited, optimized user experience for the previous and new users.

Conducting an in-depth interview is a skill that we can all learn. To do it well, you need to consider four factors:

  • The interviewee.
  • The purpose of the interview.
  • Your role as interviewer.
  • The way to conduct an interview.

We can point out some activities that can lead you through all of this process and get the most valuable insights from your users:

The first thing to consider is the purpose of your interview and research. Are you looking for general information or specific details? Do they need to know something personal or professional? It is essential to understand what you want to get out of the process so that you can guide your questions and, ultimately, the conversation.

For example, perhaps you want to understand how customers feel about your new web design. In that case, ask open-ended questions such as "What do you think of our new site design when compared to our previous version?"

But, let's imagine you are planning to launch a new app for bread delivery. In that case, you will be asking questions about the overall experience of people ordering bread, their needs, and the challenges they find in a more traditional, direct way of buying a product. Your goal will be to find the best solutions for this app and plan its features and communication style with potential customers.

It doesn't matter if you launch a new product or want to review what already exists and redesign it - you have to know your audience. You should recruit people for the interview carefully as you don't have time for mistakes. Consider the people you are going to interview. You can prepare, for instance, a questionnaire where you would ask them about themselves or their experience with what you're researching. Asking these questions helps you understand who they are and how they feel about the topic at hand. Choose respondents that represent different target groups. That can help you to get variable insights related to other approaches, knowledge, and experience.

Define the time frame for the entire study. Do you want to spend 2 or 3 weeks on them, or do you need to extend them for several months? Carefully think about the amount of people you can interview. It makes no sense to invite 150 people for a 5-minute meeting. Measure your processing capacity and adjust it accordingly. It's better to narrow down the number of respondents to 20, 10, or less, but meet with each of them for 30 or 45 minutes to have enough time to deepen their reflections and feelings.

How many people should we interview? It is up to your research time, but it is essential to do it until you find a pattern or responses, usually 5-7 people.

Think carefully about what answers and knowledge would be valuable to your project. Maybe you would like to focus on customers' behavior, how they buy something, and how they make decisions. Perhaps you can concentrate more on actual problems with the website and understand what issues your users meet when they navigate the website.

Reduce the number of questions to the important ones - check if any are not repeated in other questions. And don't be afraid to ask about some details. Be a good listener; as you conduct semi-structured interviews, there will always be possibilities to deepen some answers.

It would help if you came up with an outline or script for your questions. This is where some interviewees can get tripped up because they don't know what they're going to ask until they meet with their subject. If possible, try writing out some ideas beforehand so that everything flows smoothly and doesn't feel forced or unplanned when you sit down with your subject. A great practice is to prepare a structure for the interview. You can divide it into the Introduction, Open Questions, Specific Questions, and Closing Questions.

  • Introduction - in this part, you will introduce yourself and the goal of the interview. You should also inform the respondent about how long the discussion will take, ask for permission if you want to record it, and answer all organizational questions.
  • Open, ice-breaking questions - encourage respondents to join the discussion by asking light questions about what a person does or what they are interested in.
  • More-detailed, specific questions - Explore the main topic by asking questions related to it and linked with your goals. For instance: “What do you think about the new filtering feature on our website? Or “Why did you decide to create an account on our eCommerce website?”. It can be helpful to prepare exercises during the interview, e.g., present some images and screens and ask respondents for their choice and feelings about them.
  • Closing questions - Use the last questions to ask what the user thinks and feels about the possible plans and what they would change if they could? For instance: “What would it be if you could change anything on the website?”

You will prepare more or less three core questions for each of these parts, which you can explore later. Treat the scenario as a skeleton and guide for the interview. It would be best if you didn’t read it when you meet with the interviewee but rather treat it as a reminder of issues you want to cover with this meeting.

In-depth interviews are a great way to learn more about your interviewees' motivations, perspectives, and experiences. However, they can be biased if you don't take precautions. Here are a few ways to ensure that the information you gather is as accurate as possible:

  • Ask open-ended questions instead of yes/no questions. For example: "Can you tell me about your experience buying shoes through the web?" vs. "Do you like to buy shoes through the web?"
  • Be cautious not to influence the answer of the respondents. Sometimes you can do it without indenting. Therefore, think carefully about the way you ask some questions. Avoid leading questions that suggest what somebody should answer. For instance, instead of asking: "What do you like about new menu on our website," ask, "What do you think about the new menu on our website?"
  • Watch out for confirmation biases that can lead you to seek the answer of respondents' approval of your assumptions, expectations, or beliefs.
  • Don't subconsciously react to the answer of respondents. That can suggest that you like this answer because you feel the same, have the same interest, or are not satisfied with the response and personally disagree with it. Stay friendly, objective, and professional at the same time.
  • Review the order of questions, and check if some previous can accidentally suggest the answer for the next ones.

Ask your teammates to test questions you have written. Ask them what they think your question means, whether it is clear and what answer they would give if asked the question.

It's also crucial for the interviewer to prepare themselves mentally for the interview process. If possible, take a break from work before going into the interview so that your mind isn't clouded by tasks from the office or other obligations that might distract you from getting meaningful answers.

As an interviewer, you need to listen and actively engage with each person during their responses so that they feel comfortable talking with you about what matters most to them. Follow up on interviewee responses. Try clarifying their reactions if you are not sure you understand the answer well.

Always ask respondents if you want to record the interview. Never do it without permission! Even if recorded, it's still a good idea to take notes during the session. The best option would be to have an assistant who takes notes while you focus on the interview process, asking questions, receiving answers, deepening them if needed, and observing respondents.

You can also use recorded session transcription programs to return to some essential interview parts.

After you’ve collected data, you will need to analyze it – which can be a challenging process. One way to make this process easier is to listen back through each interview. Create a transcription of the conversion, and flag different parts of the conversation that are interesting. You can also use notes with the essential reflections and answers.

Create a report and present the most critical insights to stakeholders to make sure that they will give rise to improvement.

There are many benefits to conducting in-depth interviews, for instance:

  • They can help you learn about your users' experiences and motivations, which are essential to developing a product that will best serve them.
  • They allow you to ask questions that might not be possible with other research methods, such as open-ended questions or surveys.
  • You can learn more about how users think and feel about something. You can use them to identify patterns in how people think or behave, figure out what motivates them to do things a certain way, or get answers to questions you can't ask any other way.
  • You can observe reactions and nonverbal responses only possible in indirect meetings and one-on-one interviews.
  • They allow you to dig deeper into issues that may not be clear from simple surveys or other research methods. They allow you to explore topics that aren't covered by other methods, such as how people feel about something rather than just what they think about it.
  • They can help you to get more honest feedback.
  • They can help you understand what users think, feel, and want from your product or service. It's also great for getting feedback from customers on designs and features.
  • They're also helpful for getting information from people who don't participate in focus groups or other types of user research.
  • IDIs are an ideal way to get information from users that can't be gleaned from any other source. Many users do not have enough time, knowledge, and competence to participate in other research methods. Meeting with them personally helps to reach them and get some valuable information.
  • They can help you make future decisions with greater confidence.

In-depth interviews also have some drawbacks:

  • They can be time-consuming

They require more time in preparation and to conduct compared to other methods. You need to reserve time not only for the meeting but also to analyze it, organize results and insights and store them properly.

  • They can be expensive

Time is money. IDI can be expensive because it requires a lot of preparation, arrangement, sometimes commuting to respondents, and finally analyzing the results and preparing the report.

  • Skilled, experienced interviewers

You need skilled interviewers in a team who know how to ask thoughtful questions, when and how to deepen the answer, and have active listening skills. Finally, they know how to create an atmosphere of comfort and trust for the respondents to make them feel natural while speaking about their feelings.

  • Difficulties with recruitment respondents

It is essential to recruit people for the interviews carefully. They should represent different groups of users with variable approaches, experience, and knowledge, and even sometimes differentiate with demographic factors.

In-depth interviews are the most common research method used in UX and UI design. This is because they allow designers to learn more about their products' actual users and determine whether the product is meeting the users' needs. Taking the time to conduct this type of research is invaluable. Together with quantitative research methods, they will allow you to collect a solid database enabling you to revise the assumptions, prepare a great product that responds to user needs, and redesign and improve existing solutions to make them more user-friendly.

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