How to conduct perfect in-depth interview with your customers
In this article, we’ll talk about writing a guide for in-depth interviews of all types. Before we get to the checklist, let’s explore the basics.
What’s an in-depth interview guide?
It’s a structured list of topics the researcher will discuss with the respondent during an in-depth interview.
An in-depth interview is a flexible conversation format, not a verbal question-and-answer type questionnaire. You can change the order of topics and ask questions in similar but slightly modified formulations.
That’s why it’s called a guide – not a questionnaire, manual, list of questions, or script.
One might ask – then, why does a guide often take the form of detailed interview questions? Indeed, if only one researcher works on a project, the guide may look like a shortlist of theses for discussion.
However, quite often, a project has more than two moderators, plus you should coordinate the guide with the internal client and stakeholders. To ensure that all involved parties have an equal understanding of what will happen in the interview, we usually add a detailed description to the guide.
Why do we devote so much time to the guide in qualitative research?
The in-depth interview guide is as important as the research report itself.
A poorly written guide won’t allow you to get to the bottom of the topic and find actionable insights.
The data quality depends on how well we form the thesis, choose the questions, and prioritize them.
We understand that there is a great temptation to ask everything in one interview, but we recommend following the rule: better less, but focused and in-depth, than a lot, but with probing at the top.
Is there a one-size-fits-all guide to all cases of research?
There are no “top 10 always working questions” for interviews. Each guide is developed only for the research goals and objectives based on the target audience’s specifics. That is why you can’t take the previous, or even a similar guide, and go to the interview with it. The probability such a scheme will work is 1%.
Because even if we make repeated “measurements” (for example, in the case of longitudinal studies, when we study one target for a long time) – the world, our target audience, the context of the time – everything is constantly changing.
Issues that were relevant a month ago may not be relevant now.
In-depth interview checklist
The following list will help you to write an in-depth interview guide:
1. Start with the goals and hypotheses of the research.
The guide is, first and foremost, a reflection of the research objectives. Before you start writing questions, ask yourself, “What questions would help me get actionable insight? And when you are about to finish, go over it and check if all the research hypotheses are covered.
2. Start with a simple warm-up.
Don’t bypass the warm-up phase, no matter how much you want to go straight to the most critical questions.
The respondent needs to tune in and engage in the topic of discussion, so start with simple narrative or associative/projective questions about the category you study.
- “When I say *brand name*, what associations do you have?” (associative question).
- “Please complete the sentence: x-product, to me, first and foremost, is…?” (projective question).
- “Please tell me as a story: how long ago and why did you start using the x-product?” (narrative question).
3. Go through the category user’s conditional customer journey map.
It’s important to do this whether you’re testing a new product or solution, or exploring perceptions and experiences with existing product offerings in the marketplace.
4. Learn about existing experiences and behaviors, probe every step of the way.
Why? How? How often? Under what circumstances? It will help you understand the underlying reasons for user behavior and choice conditions based on user experience.
And in further analysis, you will be able to segment and form an explanation of why specific attributes are essential to one audience while others are important to another.
It will help you define why people perceive the same brand, product, or service differently.
5. Formulate the question correctly.
Follow the rule “open-ended questions first,” and ask closed, clarifying questions only after them.
It is wrong to ask: “Do you like x-services?” (closed question, the user can only say “yes” or “no”).
A proper way to ask is, “What do you think about x-service?” (an open-ended question that prompts you to give an open-ended answer). After that, you can ask closed-ended questions: “You don’t like the x-service? Why?”
No questions that already have a certain attitude, assessment, or frame the respondent’s answer (as long as you do not repeat the correlator’s own statement).
- For example, incorrectly: “Do you pay attention to price when choosing x-product?”
- Correctly: “How do you sometimes choose x-product?” And then, you can explore specific selection criteria (e.g., price).
6. Use a funnel of questions.
The funnels can be direct – first the general questions, then the detailed ones – and rotary – first a set of focused questions, and then the general ones.
In what situations, which funnels to use? The answer is in the category you investigate – how easy it is to rationalize. If it’s about the experience, which is self-reflexive (e.g., the choice of vacation destination and hotel), then use a direct funnel of questions.
- “When I say “vacation,” what images, associations, thoughts do you immediately have?”
- “How do you sometimes plan your vacation?”
- “The last time, how did it happen?”
But if you talk about an experience or behavior that is difficult to self-reflect or communicate (for example, the daily choice of TV shows to watch or the routine purchase of grocery bags), the question should start with the focus and then move to the general.
- “Tell us, please, when was the last time you bought a gumball? Which one did you buy?”
- “Was this your typical purchase?”
- “In general, why do you need chewing gum? Why do you buy it?”
7. Remember that at first we praise and then criticize.
Although our intelligence works exactly the same way – it is easier to criticize than to find positive arguments about a particular product, brand, or service.
So, always start your probing with the good – you will always be able to collect negative opinions in your interview. Still, it is crucial to get the criticism out of the respondent’s position.
8. Be carefull with specific terminology.
You can use industry specific terminology if you write a guide for a B2B interview and your audience is industry professionals. But in other cases, such try to make it simple. Words and phrases like onboarding, customization, feature, upgrade, deployment etc., may be unclear for the general audience.
There is a risk that your respondent does not understand you, or you will lose contact with him – provoke emotional discomfort of the person in the context of “friend-or-foe”.
9. The more questions, the better?
Yes, if you are not going to ask them all. Writing a detailed guide with many questions is helpful if we mean backup/safety questions. So, you’ll have something to ask if one of the questions doesn’t work.
Remember, if your respondent has answered questions you have not set yet – don’t ask them, even if they are prescribed in the guide. Otherwise, they can think you don’t listen respectfully to them.
How do you know which questions need to be changed because they do not work?
- If the respondents do not understand your question;
- if respondents answer formally, but you still do not get a specific answer to the question;
- if you perceive not new information but what you already knew before the survey.
The guide is ready, but what’s next?
If possible, test it with a friend or a person you know. The test works well for both sides: if you are in the role of the respondent, you can understand what questions people are comfortable answering or not.
If you are a moderator, it will allow you to “feel” the guide on the quality of the questions themselves: how logical their structure is and how unambiguously they are interpreted.
Remember, there are no good or bad, right or wrong guides. The guide should help you gather the necessary data. That is why refining it after the first pilot interviews with the target audience is acceptable.
Although the popularity of user research is growing, some people think it’s an expensive pastime that only big businesses can afford. Even large companies perceive funding for research as a cost, not an investment. In times of crisis, research budgets are the first candidates for cuts. So, is research unnecessary? Let’s try to find out.
Why user research is valuable for the company
• Relevant data. Research is a source of information about the customer perception of existing or new products that helps managers develop a product strategy according to demand.
• Customer-centric. Research helps to understand customers’ needs and pains. This information allows managers to develop needs-based products and services and optimize performance, usability, and conversion of existing services.
• Competitive advantage. A vital tool to stay ahead of competitors is to conduct comparative studies. Thanks to research, you’ll know why customers prefer some products to others, what weaknesses competitors have, etc.
• Right decision-making. Research is the best way to prevent the influence of cognitive biases, which often promote bad business and product development decisions.
Managers will never know perfectly everything about the product, customers, potential clients, and their needs, etc., so there will always be uncertainty in choosing a course of action.
But, through research, the level of uncertainty can be reduced, allowing the manager to be more confident that he made a correct decision.
The types of research
User research is a systematic collection and interpretation of information about individuals and organizations using statistical and analytical methods and techniques from the applied social sciences. Companies use it to make business decisions.
There are many typologies of research:
• By the source of information: Primary vs. Secondary
Primary is research that you can collect yourself. It is raw data collected through various ways – surveys, focus groups or in-depth interviews, data analysis, observation, etc. The secondary is the finding out data that has already been collected, analyzed, and published.
• By the main question: Quantitative vs. Qualitative
Qualitative research acquires in-depth, detailed information about the research subject. It is the collection of data that is non-numerical. Quantitative research is the collection of data that is numerical in nature.
Qualitative research answers the questions “how?” and “why?” while using quantitative methods of research, you can get an answer to the question “how much?”
• The research subject: The Attitudinal vs. Behavioral Dimension
As the Nielsen Norman Group article states , this distinction can be summed up by contrasting “what people say” versus “what people do.”
So, attitudinal research is trying to mature and analyze people’s thoughts and beliefs about the research subject. Behavioral research methods focus on understanding people’s behavior toward some products or services in question.
• The main goal: Exploratory vs. Specific
Exploratory research is general and open-ended and typically involves lengthy interviews. People take them in case of absence or lack of knowledge about the research object, the target audience, the population, etc.
Specific research people use to solve a problem identified in an exploratory study. It involves more structured, formal interviews to dive deeper into a particular topic or issue.
During exploratory research, we usually collect qualitative data. Specific study often finds their insights through quantitative data. But such a division is not compulsory.
• By the context: Natural, Scripted, Not using
The natural research approach means that the study happens during the natural use of the product. The main instrument in such a type of research is participant observation. The goal is to minimize interference from the study to understand behavior or attitudes as close to reality as possible.
A scripted study follows the particular scenario of product usage. This research focuses on the insights on specific product or service usage aspects (for example, a newly redesigned flow).
Studies where the product is not used, are conducted to study broader issues than usage and usability, such as a study of the brand, advertising, or cultural behaviors.
• By the service design/product cycle: Discover, Explore, Test, Listen 
• By the research object: market research (brand tracking, ad test, package test, concept test), UX research, customer experience research
Each typology includes different research methods. Nielsen Norman Group, in their article , propose such matrics of mixing research by subject (Attitudinal vs. Behavioral Dimension) and main question (Quantitative vs. Qualitative).
Also, below, the example of the research method mix for User-Experience Research 
Here are some examples of how to solve specific business problems:
Research is a reliable base for business decisions. It is the best way to protect businesses from incorrect steps based on past consumer behavior or intuition. Removing subjective opinions while making business decisions is the goal and strength of research. If some feature was a hit in the last version of some product, how can we be sure that it still will be the same in the future? And how may it be possible to lead the product development to the next level without asking for feedback from the people who use it?
Conducting research allows you to use data to answer those questions. By identifying and gathering feedback from your target customers, you can understand how they feel about your products and services, your brand, and your communication before you go to market.