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How to Interview Customers the Right Way

A 7-Part Evidence-Based Guide to Customer Discovery. Learn how to conduct customer interviews the right way with this evidence-based guide to customer discovery. Discover proven frameworks like The Mom Test, key questions to ask, how many interviews you need, and how to turn insights into validated product decisions so you build what customers actually want.

Aziz chaaben

2/18/202616 min read

A dark, dramatic painting of mythological figures in combat.

Introduction:

The difference between the startups that burn months building features and the ones that build momentum is simple: the winners talk to customers correctly before they build. They don’t ask for validation. They extract truth. Therefore, their decisions are grounded in behavior, not compliments.This guide breaks down the exact interview frameworks, data-backed benchmarks, and tactical structures that separate signal from noise so you never waste another year building something nobody wants.

Summary:

1: Why Most Customer Interviews Fail The statistics proving why building without proper customer discovery kills 42% of startups and costs billions.

2. The Mom Test: The three non-negotiable rules for asking questions that reveal truth instead of polite lies.

3. How Many Interviews Do You Really Need? :Research-backed numbers and real case studies showing when you've gathered enough data to make decisions.

4. The Perfect Interview Structure and Questions The exact 30-minute framework and specific questions used by successful founders to extract actionable insights.

5. Finding and Recruiting the Right People to Interview Where to find ideal interview subjects and how to get them to say yes.

6. During and After the Interview - Best Practices Critical behaviors, environment setup, note-taking techniques, and how to avoid misleading yourself with false positives.

7. Analyzing Insights and Making Decisions How to recognize patterns, avoid interpretation bias, and confidently decide whether to build, pivot, or kill your idea.

8. Conclusion

1. Why Most Customer Interviews Fail

Before we start talking about how to do customer interviews the right way we need to understand why they usually go wrong. And why this is such a big deal.

The Scale of the Problem

Some research shows us:

* 42% of startups fail because people do not need what they are selling (CB Insights)

* 72% of products that came out between 2009 and 2014 did not make as much money as they thought they would (Simon-Kucher & Partners)

* In 2010 companies in the US lost $260 billion because their products failed (University of Texas at Austin)

* For products that businesses sell to businesses 6 out of 10 new products do not make as much money as they thought they would

Sources: CB Insights - Top Reasons Startups Fail, Growth Ramp - Customer Discovery Interviews

The Three Types of Bad Data That Kill Startups

The Mom Test framework says there are three kinds of feedback that are not helpful:

1. Nice things people say. Like "That is an idea" or "I love it". These make us feel good. They do not tell us if people will actually use or pay for what we are selling.

2. What people think they will do. Like "I would use this". I would pay for that". People are not very good at knowing what they will do in the future. Research shows that what people say and what they actually do are very different.

3. When customers tell us what features they want.. They do not tell us what problems they are trying to solve. They are telling us what they think is perfect not what they really need.

Justin Jackson, who started The Mom Test says: "You can not trust what customers say they will do. You can only trust what they are doing now."

Source: The Mom Test by Rob Fitzpatrick

Why Smart People Still Get It Wrong

The problem is not that people are not smart or that they are not trying. The problem is how people think. People:

* Want to be helpful and nice to others

* Do not want to disagree with people or make them unhappy

* Think they will do things in the future that they might not really do

* Answer questions the way they think we want them to

Entrepreneurs make this worse by:

* Telling people about their idea before they understand the problem

* Asking questions that can only be answered in a way

* Trying to get people to like their idea instead of trying to find the truth

* Only hearing what they want to hear and ignoring what they do not want to hear

The Cost of Getting It Wrong

Bad customer interviews are bad news. They do not just waste your time they actually lead you to build something that is not needed. This can cause a lot of problems. For example:

• You spend months or even years working on features that nobody actually needs.

• You use up all your savings or the money that investors gave you.

• You miss out on opportunities that could have been really good for your business.

• People who could have invested in your business or worked with you start to think you do not know what you are doing.

Research from Growth Ramp, a company that specializes in talking to customers shows that good customer interviews are very important. They help you figure out how much to charge for your product what to say to customers to make them buy it what makes people want to buy it and how to position your product in the market.

If you do customer interviews badly you will make mistakes when you are making these business decisions. Quality customer interviews and bad customer interviews both affect your business and customer interviews are really, about understanding what customers want and need and what they will pay for so you can build a business.

Source: Growth Ramp - Customer Discovery Basics

2. The Mom Test - Three Rules That Change Everything

The Mom Test is really helpful because it gives you a way to ask questions that people will answer honestly. These three rules will completely change how you have conversations with customers.

Rule 1: Talk About Their Life, Not Your Idea

When you talk about your idea it changes the conversation. The Mom Test makes sure you ask questions that even your mom cannot lie to you about. People will. Try to make you feel good or tell you what they think you want to hear.

Bad question: "Do you think an app that does X would be useful?"

question: "Walk me through the last time you encountered a problem like this with The Mom Test, in mind so I can understand how The Mom Test can help with this problem.". What did you do?"

The difference is profound. The first question invites a polite "yes." The second forces them to recall concrete experiences, revealing their actual workflow, pain points, and workarounds.

Source: Atlanta Ventures - The 3 Rules from The Mom Test

Rule 2: Ask About Specifics in the Past, Not Generics or Opinions About the Future

People are terrible at predicting their future behavior. But they're very good at recounting what they actually did.

Bad question: "Would you pay $50/month for this?"

Good question: "What do you currently pay to solve this problem? Show me your current solution and walk me through your last invoice."

As one founder discovered conducting B2B interviews: "Questions around the business drivers, the problems, the intensity of the pain, the problem ownership, the decision-making units, and the buying processes help you understand which problems matter most."

Source: Lean B2B - B2B Customer Discovery Questions

Rule 3: Talk Less, Listen More

The more you talk, the less you learn. Your job in a customer interview is to extract information, not to convince, educate, or impress.

A good rule of thumb: You should be talking less than 10% of the time. If you find yourself explaining features, defending design choices, or pitching benefits, you've lost control of the interview.

Instead:

• Ask open-ended questions

• Use silence strategically (people fill silence with valuable information)

• Follow up with "Tell me more about that" or "Why is that important?"

• Take extensive notes or record (with permission) so you can focus on listening

Source: tl;dv - The Mom Test Guide

Putting It Into Practice: Question Transformation

Here's how to transform common bad questions into Mom Test-compliant ones:

Instead of: "Do you think this is a good idea?"

Ask: "Tell me about the last time you faced [problem]."

Instead of: "Would you buy this?"

Ask: "What are you currently doing to solve this? How much does that cost you?"

Instead of: "What features would you want?"

Ask: "Show me how you currently do this. What parts of the process frustrate you most?"

3.How Many Interviews Do You Really Need?

One of the most common questions is: "How many customer interviews should I do?" The answer varies by stage, but research provides clear guidance.

The Research-Backed Numbers

Early Problem Discovery (Pre-Product):

• Harvard Business School recommendation: 5 interviews per persona with consistency in each interview

• Growth Ramp standard: 30 interviews for initial client projects

• Common range recommended: 10-20 interviews to identify consistent patterns

Sources: Harvard Business School - Customer Discovery Basics, All Factors - Customer Discovery Interview Questions

Real-World Case Studies

Case Study 1: Winware (300+ Interviews)

Before building any product, the Winware founder spoke to more than 300 different companies. He met with various roles within each company, conducting 2-4 interviews daily. Each conversation helped narrow down the target audience and focus on the ideal customer profile (ICP).

Results: This extensive research allowed them to make better decisions, reduce burn rate on initiatives that wouldn't yield results, and focus the team on the most probable path for success.

Case Study 2: Penpot (Continuous Discovery)

The Penpot team conducts ongoing customer interviews to validate new features. As their team describes it: "An interview gives you the chance to pitch your vision more informally and get an unfiltered reaction to it. Sometimes that reaction is quite bland, [or] you get a sequence of 'wow!'s and 'aha!'s."

Key insight: They don't ask customers "what they want" from the product. Instead, they listen for unmet needs and then pitch solutions customers may have never imagined.

Source: Jeff Gothelf - How 3 Startups Built Their Customer Discovery Practice

When You Have "Enough"

You know you've done enough interviews when:

• You start hearing the same problems and stories repeatedly (pattern recognition)

• You can accurately predict how the next interview will go

• New interviews stop revealing new information about the core problem

• Multiple people have described the same painful workflow or workaround

However, as one B2B researcher notes: "You shouldn't put a limit on the number of meetings you can have with prospects. As a general rule, it takes more interviews in B2B than in B2C."

The 10% Response Rate Benchmark

When you are trying to get people to agree to interviews Growth Ramp says you should try to get least 10% of people to respond within 24 hours. This is what you should be aiming for. If you are not getting this responses then you need to make your outreach campaign better.

So if you send emails to 100 people you think might be good, for an interview you should get least 10 positive responses back within a day. If you do not get this responses then you need to make your outreach message or the people you are targeting better.

Source: Growth Ramp - Customer Discovery Interviews

4.The Perfect Interview Structure and Questions

Now that you know the principles, let's get tactical. Here's the proven structure and specific questions that extract truth instead of polite lies.

The 30-Minute Interview Structure

Based on research from Lean B2B and multiple successful founders, here's the optimal flow:

Greetings (2 minutes): Greetings are exchanged and the prospect is made comfortable through shared context (e.g., "How's the weather in ___?"). This isn't wasted time it establishes psychological safety.

Qualification (3 minutes): Ask questions to understand the role and situation of your prospect. Confirm they're the right person and that they actually experience the problem domain.

Open-ended questions (20 minutes): The bulk of time. Your goal is to understand and prioritize the problems of your prospects. This is where the real learning happens.

Closing (5 minutes): To move the relationship forward, try to close on another meeting, a referral, or some other form of commitment.

Note review (10 minutes, after the call): After the meeting (without the prospect), review your notes to ensure you're not losing information and to quickly adjust to feedback.

Source: Lean B2B - Customer Discovery Interview Structure

The Essential Questions (From Multiple Expert Sources)

These questions have been amalgamated from The Mom Test, Ash Maurya (Lean Startup), Y Combinator Startup School, and successful founders:

Warm-up Question:

• "How does [area/topic X] affect your life/business?" - Provides background information and allows you to evaluate relevance of other answers.

Problem Discovery:

• "What challenges do you face with X?" - Finds out if there's an acknowledged problem

• "Tell me how you deal with X today?" - Reveals current jobs-to-be-done and existing solutions

• "Walk me through the last time you encountered this problem. What did you do?" - Gets specific past behavior, not hypotheticals

Current Solution Deep-Dive:

• "What other solutions have you tried?" - Reveals competitive landscape and what didn't work

• "What do you like/dislike about your current approach?" - Identifies opportunities and deal-breakers

• "Show me your current workflow/tool/process." - Observation reveals what words can't

Cost and Value:

• "How much does this problem cost you today?" - Quantifies pain in dollars or time

• "What do you currently pay for your solution?" - Establishes willingness to pay and budget

• "If you could wave a magic wand and solve this instantly, what would that be worth to you?" - Uncovers perceived value ceiling

For B2B Specifically:

• "Who else is involved in decisions like this?" - Maps the decision-making unit

• "What's your typical buying process for tools like this?" - Reveals sales cycle and objections

• "What would need to be true for you to switch from your current solution?" - Identifies switching costs and barriers

Sources: Medium - Customer Discovery Done Well, Insight7 - Validating B2B Concepts

Critical Follow-Up Techniques

When someone gives you a vague answer, dig deeper with:

• "Can you give me a specific example?" - Forces concrete details

• "Why is that important to you?" - Uncovers underlying motivations

• "What happened next?" - Extends the narrative to reveal more context

• "How often does this happen?" - Quantifies frequency and urgency

5.Finding and Recruiting the Right People to Interview

Having great questions means nothing if you're asking the wrong people. Here's how to find and recruit the right interview subjects.

Who Should You Interview?

The best interview subjects are:

• People who actively experience the problem (not those who might in the future)

• Early adopters who have already tried solutions (they're motivated buyers)

• People with budget/authority to purchase solutions

• Those who feel the pain frequently (daily/weekly, not monthly/yearly)

As one researcher notes: "If they haven't looked for ways of solving it already, they're not going to look for (or buy) yours."

Where to Find Them

Start with warm channels, then expand to cold outreach:

Warm Channels (Highest Success Rate):

• Your email newsletter subscribers

• Your business Rolodex and email contacts

• LinkedIn connections (personal network)

• Investor networks (ask for intros)

• University professors in relevant fields (great for warm intros)

Community Channels:

• Relevant subreddits

• Facebook and LinkedIn groups

• Slack communities

• Industry meetups and conferences

Cold Outreach (When Necessary):

• LinkedIn direct outreach

• Content marketing to drive inbound leads (write LinkedIn posts, blog articles)

• Paid channels like Facebook Ads, MTurk (use sparingly and carefully)

One successful founder's journey: "Initially I did cold outreach on LinkedIn. With a relatively low success rate, I then began reaching out to my personal network as well as my investor's networks. Finally, I began experimenting with content marketing to drive inbound leads not for sales (at least not yet) for learning. Writing compelling content on LinkedIn began to attract the audience I was looking for."

Source: Jeff Gothelf - Startup Customer Discovery Practices

The Art of the Interview Request

Your outreach message should:

• Frame it as research (not sales): "I'm doing research on [topic]" works better than "I'm building a product"

• Offer value: "I'd love to share the results of my research with you"

• Be specific about time: "Would you have 20-30 minutes this week?"

• Make it easy: Provide a calendar link or 2-3 specific time options

• Don't mention your product or solution (yet)

The Snowball Technique

Every interview should end with: "Do you know anyone else who faces similar challenges that I should talk to?"

This technique:

• Turns cold outreach into warm intros

• Validates that you're talking to the right people (they know others like them)

• Dramatically increases your response rate for subsequent interviews

As one expert notes: "It's hard to find the right people, we shouldn't miss this opportunity."

Source: Studio Zao - 10 Tips for Customer Discovery Interviews

6.During and After the Interview - Best Practices

The interview itself is only part of the process. What you do during and after determines whether you actually learn anything useful.

Setting the Right Environment

Create psychological safety from the first moment:

• If meeting in person: Choose a cozy, comfortable room. Sofas beat boardroom tables.

• Spend the first few minutes creating emotional connection

• Make it feel like a conversation with a friend, not a formal interview

• The more comfortable they feel, the more they'll open up

Set expectations upfront: "I want to be completely honest I'm here to learn, and the most helpful thing you can do is be brutally honest with me. Please don't worry about hurting my feelings. If something sounds bad or wouldn't work, I need to know that now."

Source: Studio Zao - Interview Best Practices

The Two-Person Team Approach

Harvard Business School recommends conducting interviews as a "discovery team" with two to three people:

• One person leads: Asks questions, maintains flow, builds rapport

• Others observe and take notes: Capture big beats, strong emotions, and specific quotes

• Backup can correct the lead if they start asking wrong questions

Why this matters: The lead can focus entirely on listening and responding, while the note-taker ensures nothing important is lost. As one founder noted: "When you're talking with customers, you likely won't be able to capture everything. Instead focus on getting the big beats (a connection they can provide, a pain point, a follow-up task) and the strong emotions."

Sources: HBS - Customer Discovery Basics, Frank Thoughts - The Mom Test

Critical Behaviors During the Interview

Resist the urge to talk about your idea: Most people can't help themselves. They want to explain why their solution is cool. Don't. As one researcher emphasizes: "We try to keep the conversation focused on customers' problems, that's the place to start. If they keep suggesting new features or what we should do some people just can't help it we gently take them back to the problem side: what is their frustration and how do they solve it today?"

Don't ask "what are your problems": This question makes people struggle and creates a bad start. Instead, walk them through their actual workflow and watch for friction points naturally.

Use the "Five Whys" technique: As I-Corps teaches: "It is important during the customer discovery process to uncover the foundational cause of an issue that a customer has. If they say they have a problem, ask them: 'Why do they have a problem?'" Keep asking why to get to the root cause.

Control your facial expressions: When they say something you didn't want to hear, your face will betray you. Practice maintaining neutral expressions, especially during bad news.

Source: I-Corps Hub - Customer Discovery Best Practices

After the Interview: The Critical Review

Immediately after each interview (within 10-30 minutes):

• Review and clean up notes while memory is fresh

• Transfer insights to a central repository (spreadsheet, Notion, etc.)

• Categorize key insights: problems, workarounds, costs, quotes, objections

• Record any commitments or action items

• Note what surprised you or contradicted your assumptions

One founder's advice: "Even if the way you initially capture the interview is in a weird way (a napkin or a paper plate, for example) make sure to transfer them to a clear place of storage for you and your team to refer back to. Even better yet, make sure to take the key data from these interviews and align them to categories in an Excel sheet to help sort through the most important takeaways."

Avoiding False Positives

Harvard warns: "In conducting interviews, avoid false positives. These can occur when interviewers hear what they want in seeking validation and when people say what they think you want to hear."

Watch out for:

• Enthusiasts who love every idea (interview skeptics too)

• People saying "yes" without commitment (money, time, introductions)

• Your own confirmation bias filtering out negative signals

7. Analyzing Insights and Making Decisions

Raw interview data is worthless without proper analysis and action. Here's how to turn conversations into validated business decisions.

The Team Interpretation Problem

A common anti-pattern identified in The Mom Test: The founding team's "businessperson" does 100% of the customer interviews and reports the takeaways to the team.

Why this fails:

• Creates an imbalance of power (the interviewer can win any argument by saying "it's what the customer wants")

• Customer conversations are subject to interpretation - having a single interpreter is dangerous

• The rest of the team doesn't develop customer empathy or understanding

Solution: Have the entire founding team involved in at least some interviews. Everyone should hear customer pain firsthand.

Source: Michael Lynch - The Mom Test Summary

Pattern Recognition: What to Look For

After 10-15 interviews, you should start seeing patterns:

Strong Signals (Green Lights):

• Multiple people describe the same painful workflow

• They're actively searching for solutions right now

• They've already spent money trying to solve it

• The problem occurs frequently (daily/weekly)

• They can quantify the cost in dollars or hours

Weak Signals (Red Flags):

• "That's an interesting problem" but no current solution attempts

• Hypothetical interest ("I would use that") without past behavior

• Each person describes a completely different problem

• The problem happens rarely (quarterly/annually)

• They can't articulate the cost or impact

The "Wow!" vs. "That's Cool" Test

When you eventually do show a solution concept (after thoroughly understanding the problem), the Penpot team looks for specific reactions:

"An interview gives you the chance to pitch your vision more informally and get an unfiltered reaction to it. Sometimes that reaction is quite bland [or] you get a sequence of 'wow!'s and 'aha!'s."

Good reactions:

• "Wow!" or "Aha!" - Genuine excitement

• "When can I buy the prototype?!?" - Immediate commitment signals

• "This solves exactly the problem I had last week" - Recent, specific pain

• They immediately start describing how they'd use it (unsolicited)

Bad reactions: "That's so cool. I love it!" (polite but non-committal)

Source: Jeff Gothelf - Startup Discovery Practices

Decision Framework: Build, Pivot, or Kill

After your interviews, you need to make a decision. Here's the framework:

BUILD (Green Light):

• Consistent problem across 60%+ of interviews

• People are actively spending money/time on workarounds

• Clear willingness to pay at a price that works for your business model

• You can reach these customers efficiently

PIVOT (Yellow Light):

• The problem exists but for a different customer segment than expected

• Your solution addresses a symptom but not the root cause

• There's a problem but your approach won't work (need different features/pricing/delivery)

• Mixed signals that require more focused investigation

KILL (Red Light):

• Nobody actually has this problem in their daily life

• They have the problem but aren't motivated to solve it ("nice to have" territory)

• Existing solutions are "good enough" and cheap/free

• The economics don't work (can't charge enough to build a business)

As I-Corps emphasizes: "Sometimes during your customer discovery process you will find out that your innovation doesn't meet the needs of your potential customers. If you hear that same message from a large number of interviews it can be disappointing. However, as far as I-Corps is concerned, this is a great success."

Better to find out now than after months or years of development.

Your Customer Interview Checklist

Before you start building anything, ensure you can answer:

• Who experiences this problem? (Specific segment)

• How painful is it? (Frequency and intensity)

• What do they do today? (Current solutions and workarounds)

• What does it cost them? (Money, time, or opportunity)

• What would they pay? (Based on past behavior, not hypotheticals)

• Who decides to buy? (For B2B: the full decision-making unit)

• Where can I find more people like this? (Distribution channel)

If you can't answer these questions with confidence after your interviews, you need more conversations or you're asking the wrong questions.

The goal isn't to gather data. The goal is to find truth. And truth, as the statistics show, is the difference between the 42% who fail and the minority who succeed.

Conclusion:

When you skip disciplined customer discovery, you trade evidence for optimism. You mistake compliments for demand. You confuse interest with intent. And therefore, you commit months of execution to assumptions that were never validated. Customer interviews are not a formality. They are your risk filter.Do them right, and you uncover urgency, budget, decision-makers, and real pain. As a result, every line of code, every marketing message, every pricing decision rests on solid ground.