6 Things To Know About Customer Development and User Interviews (🍕#4)

From developing assumptions and hypotheses, to asking the right questions in interviews and blending qualitative and quantitative data.

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The importance of building for your customer cannot be emphasized enough.

Often founders (including myself with my first company) come up with an idea that they think is fantastic, start building it without any validated learning, and ship a product in search of a solution.

This is the mindset of “If I build it, they will come”. The truth is, they don’t. And often founders find themselves in a position of having a working product, no users/customers, and the need to start iterating with limited time and runway. 

Only once they start speaking to potential users and customers do they start learning about what the customer actually needs and building the right thing.

If you’re starting your own business, you’re essentially the product manager. And as a product manager you need to be taking a lean and customer-centric approach — where you’re building an MVP based on early feedback, iterating on quantitative and qualitative data, and making all your product decisions around the customers.

This Slice will show you (1) how to avoid the pitfall of not validating before building a product by conducting customer interviews and, subsequently, (2) how to not waste time, money, and motivation.

But first, what actually is customer development?

Customer development is a framework developed by Steve Blank. Essentially, it’s the practice of establishing a continuous and iterative line of communication with your customers to find opportunities and mitigate risk. 

Speaking to customers helps with idea generation, testing of hypotheses, getting feedback, and changing your product toward the goal of product market fit.

1. What are your assumptions and hypotheses?

Before speaking to customers, one of the first exercises you need to do is write down your assumptions and your hypotheses.

Your assumptions are what you believe to be true in order for your business to have work. It’s why you think your idea will work, what behaviour you predict from customers, and the reasons behind them. 

Imagine you were starting Airbnb, the first shared accommodation platform that had an extremely contrarian assumption — people will pay to stay on a stranger’s couch.

This was an assumption that needed to be true for Airbnb to work. 

Once you have your assumptions written down, it’s useful to put them in a table with two other variables: risk and complexity.

Risk means how important it is for this assumption to be true for your business to work. High risk means it is fundamental to the idea. Complexity means how hard it is to test and validate.

Once you have this table, start forming hypotheses in this format, and then testing the ones that are high risk and easy complexity first.

Basic format:

We believe that _(target user) will _(predicted action)_ because _(reason)_.

Our mock Airbnb assumption can be converted to this  hypothesis.

We believe that travelers will book accommodation online and stay on a strangers couch because it’s cheaper than a hotel and a more personal experience.

2. Who you should be talking to

A great way to start testing your hypotheses out is by running user interviews.

As a founder or PM, you should be speaking to (target) customers at three stages — during validation, development of the first version, and iteration.


Before you’ve built anything, your goal is to speak to your target audience to see if your product solves a real problem. 

One common mistake is trying to sell your idea during an interview. This is a waste of time. You’re not actually gathering any useful data and can easily be falsely convinced that your idea is great as customers may not answer truthfully when a binary, “do you like this idea”. 

Think about who you think has this problem and would want to use your product. Then,  reach out to them asking for a quick conversation. 

Development of V1

At this stage, you don’t have any customers using your product yet. But, hopefully, you’ve at least started gathering email addresses of early adopters from a landing page.

Start including those who’ve expressed early interest in your solution with product development. Your goal here is to speak to these customers-to-be and get them to help with feature triage — the process of working out what features to prioritize in product development.


During this phase, you’re improving your product and speaking to actual users and customers to see (1) if they are enjoying your product, (2) who’s getting the most value from it, and (3) what features can be cut or need to be added.


3. The different types of interviews 

User interviews are the most useful way to gather qualitative data and are vital at the early stage of your startup. There are 4 main types of interviews you should be conducting.

Exploratory interviews

These are the most freeform types of interviews. The goal here is to work out if your target user experiences the problem you assume exists and if they’d be open to a solution.

You want to ask open-ended questions and listen as much as possible. The more they speak, the more data they reveal and insight you get about them as a customer. For example, say you were a product manager at Airbnb in the early days. A good exploratory question would be, “Tell me about the last time you travelled, and what could have made your trip better?”

Validating interviews

Once you have your hypotheses, you can use these types of interviews to test your theories following the scientific method. 

These interviews are naturally subject to a lot of bias because founders often tell users the idea, and ask things like, “Does this seem like a good idea?”

Most people are kind and will lie. Avoid bias by listening more, and only at the end of the interview explaining your idea as objectively as you can. 

You don’t want to be married to your idea, this is the time to make any types of changes necessary, so avoid protecting your ego and go in with the mindset of coming out with change. 

A tactic I’ve found useful to help myself avoid selling an idea, and to help the user feel comfortable being honest, has been to be candid with the person I’m speaking to, letting them know the purpose here is to understand their problem and see how we could solve this for them.

Satisfaction interviews

Once you have a working product and customers, you can run these interviews to find out the general sentiment toward your product.  This will facilitate making improvements around frustrations and optimizing on winning features. 

Efficiency interviews

The goal here is optimization — you want to find out how to improve your product to better serve its purpose. During these interviews, you want to find our things like when they are using your product and where they find it most helpful.

An important point to remember, especially during type 1 and 2 interviews, is that the topic is not your product. You want to find out information like: who your customer is, what their habits are, and when and why do they need your product. These interviews are all about understanding consumer needs and industry-wide pain points.

4. Good and bad questions

When you’re conducting a user interview, you want to avoid questions that could bias the customers’ answers. Asking good questions that encourage honest responses are key to gathering useful data.

Ask opened ended questions

You want to give them as much flexibility as you can to talk openly about the problem — open-ended questions make it easier for them to talk more. Ask “what” and “how” questions that allow the user to answer expansively and talk more. Don’t be afraid to let there be a little bit of silence if they stop, just nod to show you’re listening — people hate awkward silence and will fill the gap by talking even more.

Don’t ask leading questions

Avoid asking questions that essentially include the answer you’re looking for. The last thing you want to do is influence their answer and ruin your interview. For instance, “I agree with you, booking a place to stay is hard, it would be really awesome if there was an app that allowed you to book a spot on someone’s couch, don’t you think?”. 

Don’t ask binary questions

Try not to ask questions that only really have two possible answers. The goal is for them to do 90% of the talking, and these questions give such short and generally useless answers besides perhaps in a satisfactory type interview.

Don’t ask questions that might make them lie

People generally want to avoid  hurting your feelings. Asking questions like, “do you like my idea?” put them in an uncomfortable position that might make them lie.  Ultimately, this information is useless since you have no idea whether it’s a genuine response.

If you ever get stuck in an interview and are not sure what to say, try this: “That’s really interesting, can you tell me more?”. It throws the ball back at them to continue their chain of thought, revealing more to you.

5. Running the interview

Your interviews should be structured and your notes documented. It’s important to have a plan for interviews before you sit down and start speaking to people. The benefit of this is keeping interviews on track and making sure you’re diving into the topics that are most important for you. A good interview is a balance between structure and freeform - it’s about going through questions but allowing customers to speak freely and following that flow.

Below is a useful template for keeping interviews structured and capturing notes, and keeping in mind you should allow questions and answers to be natural. It’s ok to skip around, not necessarily cover everything, and ask questions you haven’t written down.

Interviews are often done in rounds, especially for larger projects. This means you start off with a set of questions and topics, speak to a group of people, and based on what you find you iterate and have new questions for the next round.  

Speak to the right amount of people. You’ll need to apply some judgement here depending on the nature and risk of the project, and who the intended user/customer is and how hard they are to reach - but usually an efficient sweet spot is 5-10 interviews per round. 

Be sensitive to their time, and shepherd the conversation. Your interviews should be around 30-45 minutes at most -- your customers are doing you a favor and you want to be mindful of their time. This is usually enough time to cover important topics and allow for natural conversion. It’s good to let people go off track sometimes as it can uncover useful information, but again, apply judgement and shepherd the discussion back to what's relevant if needed. 

6. Finally, combining qualitative and quantitative data

Speaking to customers is vital in gathering qualitative data and being in sync with your customers’ ever-changing needs. 

However, as a PM it should be only one item on your data diet, not the whole thing. 

Once you have a working product, you need to be measuring hard numbers related to growth, engagement, and retention — this is where quantitative research comes in.

There are many platforms, like Looker, Amplitude, Google AnalyticsMixpanel, and Hotjar that are great at helping you collect and report on this type of data.

Combining quantitative and qualitative data is key to forming the best overall impression of where you stand, and helping you make the best decisions around iteration and optimisation.


Every week, I share my experiences, insights and perspectives on product, growth, people, and anything else that I’ve found helps me have a happier and more meaningful career in product management.
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