The One Biggest Error in Customer Interviews: Mistaking Opinions For Facts

Added on by Alexander Osterwalder.

Customer interviews are a great technique to quickly and cheaply get early customer insights. However, many of the executives we work with commit a dangerous error: they mistake customer opinions for hard facts. We explain.


It’s extremely easy for your customer interviews to go on the wrong track if you don’t pay attention to the difference between opinion and fact. People who are not trained to do good customer discovery will immediately start asking interview subjects questions like, “Do you like this idea?”, “Which solution do you prefer?”, “Would you buy this?”. These questions will solicit opinions. Yet, experience shows that people rarely do what they say.

Your questions should instead probe for hard facts. For example, don’t ask, “What do you think  the challenge is?”.  Instead you can ask, “When is the last time you struggled with this particular challenge?, “Can you describe what you were wrestling with, the last time you faced this challenge”, or, “When is that last time you googled a solution for this particular problem?”.

Another common error we’ve seen people make in customer interviews is that they’re satisfied with superficial evidence when they ask for facts. Your task in a customer discovery interview is to dig deep and uncover hidden gems. Dig out quantitative evidence (and concrete instances) as much as possible. For example, ask “Why is this such a challenge?”, “How do you concretely measure success or failure related to this challenge”. When an interviewee says “I need a faster solution”, immediately ask “how much faster?” and “what’s the minimum improvement that still qualifies as success?”. How can you judge if your solution creates customer value, if you can’t quantify how your customers measure success and failure?

When it doesn’t make sense to ask for quantitative metrics, go for concrete instances to measure success and/or failure . I remember helping the tourism agency of a Gulf nation perform customer discovery interviews. To understand how visitors to their nation qualify a trip as a unique experience they would ask “Tell me of the last time you had a unique experience” and “what exactly made that experience unique?”. This line of questioning provides much stronger evidence than if they had asked “What do you think a great experience looks like?”.

Asking for opinions rather than facts is the single biggest error in customer discovery interviews. This is a problem because implementing a new idea based on people’s opinions is usually a dangerous path. It doesn’t decrease the risk of a new idea as much as the investigation of facts. Pursuing something that’s based on evidence from the past is much better, even if your solution does something new. Your task is to connect new behaviour to evidence from the past. Evidence from the past strongly indicates future behaviour.