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12 rules of a customer interview

Little but important things that are not covered in The Mom Test

Mom, look, I’m thinking of building this application with recipes. You can download it on your device and browse recipes that you like, tag your favorite, save and share them with your friends. Do you think it’s a good idea?

— Well…hmmm… sure, honey. Sounds amazing!

This customer interview gone 100% wrong from The Mom Test by Rob Fitzpatrick is probably known to every product manager, UX designer, and bootstrapped founder (if it’s not — stop doing what you’re doing right now, and go read this book). Rob has identified key problems with running a customer interview and offered some very useful hands-on advice on how to do it. However, when it comes down to running a real interview there are some other important details that you should be aware of. These are tips and tricks covered in detail in a new book on customer discovery Deployed Empathy by Michele Hansen. So, let’s dive in.

The main purpose of an interviewer during a customer interview is to establish an atmosphere of trust so that a customer opens up and tells everything about their emotional, social, financial and other motivations. How do you do it?

Rule 1. Use a gentle tone of voice

Not too soothing but definitely not harsh. Make an effort to sound friendly — even if you’re talking to a customer that canceled a subscription, or left a negative review.

Rule 2. Validate them but not encourage them

This is a very important rule. In a friendly conversation, you might have with someone you’re inclined to encourage a person (“You did great!”, “That was a smart move”, “No worries, it’s fine”). Not during the interview. A customer starts explaining why they did that mistake. Would you say “No problem, it’s fine”. No. An expression like this instantly puts you in a judgmental position (you’re the one who decides if it’s fine or not) and destroys trust. Say “I can see why you did it” or “It makes sense”. Just validate the actions without judging them.

Rule 3. Leave pauses for them to fill

When you don’t get an immediate response your natural inclination is to rush with suggestions or move to the next question because pauses feel awkward. But during customer interviews, you can keep them up to 1 minute! “Why did you close this tab?” — and wait. Don’t offer options (“because it felt like a right thing to do? or?”) Wait for what they say. Wait. And wait. If they are silent, prompt a bit “Is there something in my question that confuses you”.

Rule 4. Mirror and summarize their words

Mirroring and summarising is a great NLP technique that comes in handy in customer interviews. They both contribute to building trust. Also, they help to clear up the situation if you’ve got the answer wrong. Example: — I was so frustrated with this feature. We tried to implement it for 2 weeks but finally had to give up and switch to another solution.So, let’s make it clear: you made effort to implement the feature for 14 days and then chose another service provider?

Rule 5. Don’t interrupt

Even if you disagree. If you feel that customer is being too boring and detailed in their explanation. Let them talk. Don’t offer your advice, view, or personal experience. The only comment you can make while the customer is talking is “mmmmhhhh”. Or nothing at all.

Rule 6. Use simple wording

It’s not because your customers are not as intelligent as you. It’s because words tend to be multilayered. Have a hint of meaning. The simpler the words — the less space for a mistake in mutual understanding. Example: – What are your objectives? — complicated question. — So, can you give me the big picture of what you’re trying to do? — simple question.

Rule 7. Ask for clarification, even when you don’t need it

It also contributes to establishing trust. And eliminates the chance for mistakes. Say: — I just want to make sure I have this correctly. First, you open up a new browser tab, then you open your email in your browser, then you open the calendar in your browser?

Rule 8. Use their words and pronunciations

This rule imposes a fat big NO on every contradiction you might have. Even if you disagree with customer’s pronunciation, or any other mistakes they might make in their speech. Even more, to establish trust you shouldn’t ignore the mistake — accept it as the right way to put things. If they say “I prefer to do the search in Groogle”. Say “When was the last time you did the search in Groogle?”

Rule 9. Don’t explain anything or get defensive

This is particularly tough when you’re running user tests on the first prototype. You think that everything is so obvious, there’s no room for mistake, UX is easy enough for a 3 yo to figure out what to do. But you ask a customer to do something and they go in a totally wrong direction. And then say “Why it didn’t work as I expected, something wrong with this app”. It’s tough and frustrating but you can do it. Instead of telling what to do, say “Can you tell me how you expected it to work?”

Rule 10. Build on what they say

If you played impromptu games you’ll manage to do it fast. If not — take some time to practice. Here’s a rule: never say “No, but”. Whatever a customer says — accept it as a reality and go from there. They say “I’m an astronaut” wearing a cowboy hat — say “Would you mind telling me how it feels being an astronaut”.

Rule 11. Let them be an expert

Again, if they say “I’ve been using your washing machine to cook pizza”… Ask “Can you tell me more about your process of cooking pizza in a washing machine?”

The worst-case scenario — they will realize their mistake. The best case — you’ll learn a new way to cook pizza.

Rule 12. Ask about past or current behaviour not about things they would or could do

This rule was covered in detail in The Mom’s Test but it never hurts to repeat. Never ask “If I build this app that solves your problem would you pay for it?” (I know, some actually make this recommendation but they have absolutely no scientific ground). Ask how they do things now, where do they look for solutions, and how much they pay for them now.

If you want to keep this rules close by, I have a Comic book where all of them are depicted in a funny way to better remember them. It's free. The book is here.

One of the pics from a book:

If you need more information on this subject feel free to contact me on Twitter or LinkedIn (DMs are open) I'm also available on ProductHunt if you prefer this network.

You can get additional information on customer interviews here:
— The Mom Test by Rob Fitspatrick
— Deploy Empathy by Michele Hansen (
— How, When and how to conduct User Interviews (
— How to conduct user interviews that actually uncover valuable insights (

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