The fifth and final day of the sprint is all about interviewing your (target) customers and learning from how they interact with your prototype.

Interview

“Five is the magic number”, is the point that Knapp, Zeratsky and Kowitz are making in Sprint with regard to the number of people to interview. The value of this number of interviewees was proven by usability expert Norman Nielsen who found that typically 85 percent of problems were observed after just five people (see Fig. 1). “The number of findings quickly reaches the point diminishing returns,” Nielsen concluded. “There’s little additional benefit to running more than five people through the same study; ROI drops like a stone.”

When it comes to conducting the actual interview, having a structured and consistent way of running these conversations is critical. Knapp, Zeratsky and Kowitz write about the “Five-Act Interview”, which consists of the following stages (see Sprint, p. 202):

1. A friendly welcome to start the interview
2. A series of general, open-ended context questions about the interview
3. Introduction to the prototype(s)
4. Detailed tasks to get the customer reacting to the prototype
5. A quick debrief to capture the customer’s overarching thoughts and impressions

The book also provides some useful tips for the interviewer, asking open-ended and ‘broken’ questions (pp. 212 – 215):

• DON’T ask multiple choice or “yes/no” questions – “Would you …?””Do you …?””Is it…?”
• DO ask “Five Ws and One H” questions – “Who …?””What …?””Where …?””When …?””Why …?””How …?”
• Ask broken questions – The idea behind a broken question is to start asking a question – but let your speech trail off before you say anything that could bias or influence the answer. For example: “So, what … is …” (trail off into silence)

Fig. 1 – Why You Only Need To Test With Five Users

Learning

Ultimately, this is what the fifth and final day of your sprint is all about: finding the end to your sprint story. Once you’ve had a chance to see how your customers react to your prototype, you’ll be able to answer your sprint questions and decide on next steps. For example, if you and your team take interview notes as a group during the five interviews, you should be able to do a good recap of all your learnings, answer the original sprint questions and decide on what to next. For example, a common next step would be to make a go/no go decision about a particular product idea.

Main learning point: In “Sprint”, Knapp, Zeratsky and Kowitz offer a very cost-efficient way to explore product questions and solutions before committing to an idea (and a large investment of time, money and effort). The reality is that as a product manager you’ll almost always will have to take a punt, but being disciplined about doing sprints and continuous discovery will help you make better informed decisions, based on real customer feedback.

Related links for further learning:

1. https://marcabraham.wordpress.com/2015/06/24/interviewing-customers-to-explore-problems-and-solutions/
2. https://www.nngroup.com/articles/why-you-only-need-to-test-with-5-users/
3. https://marcabraham.wordpress.com/2014/04/20/how-to-do-effective-user-interviews/
4. https://marcabraham.wordpress.com/2014/11/21/julia-shalet-explains-about-user-research-at-the-mobile-academy/
5. https://marcabraham.wordpress.com/2015/10/19/collaborative-user-research-learning-from-erika-hall/