Customer interviews are the cheapest research you can do, and one of the most often done badly. Leading questions and polite customers can give you confident answers that are completely wrong.
These simple rules help you hear what customers really think.
Ask about the past, not the future
People are poor at predicting what they will do. Instead of asking "Would you use this?", ask "Tell me about the last time you had this problem. What did you do?" Real behaviour is a far better guide than good intentions.
Questions that work
Walk me through how you handle this today.
What is the hardest part of that?
What have you tried to fix it, and why did it not work?
What would make this worth paying for?
Questions to avoid
Avoid questions that suggest the answer, like "Don't you think it would be easier if...". Avoid pitching your idea in the middle of the interview. Once customers know what you want to hear, they will politely say it.
Make sense of what you heard
Write notes straight after each call. After eight to ten interviews, look for patterns: the problems that come up again and again, the words customers use and what they already pay to solve them. Those patterns are where your best opportunities are.
The short version
Ask about real past behaviour, keep your idea out of the conversation and look for patterns across many interviews. Ten honest conversations beat a hundred survey answers.
