Preparing for a Product Manager Interview

So you’ve worked hard on preparing the product manager application and you’ve managed to snag an interview invitation. You still have a lot of work ahead of you as PM interviews require a fair bit of preparation (especially if it’s your first PM job). If you have not already, I would urge you to read Ken Norton’s (ex Google PM) excellent advice on hiring PMs.

Every company is likely to have a different approach to interviewing and your best bet is to look at the company’s Glassdoor and Quora pages for interview information. This tends to be easier for larger companies and much harder for the smaller ones. In general, the questions that you will encounter can be roughly classified under the following categories.

Estimation Questions

• How many aeroplanes are in the sky right now?
• Estimate the annual revenue of Google in China?

These may seem like trick questions but they are meant to test your ability to quickly estimate the size of a market which is a useful skill to uncover new market opportunities or to test the viability of new features. These are also called Fermi problems, named after the physicist Enrico Fermi who was famous for making accurate estimations with very little data. The test is more about the method you use rather than the final number that you come up with. This type of question is very popular in the consulting interview and a google search will give you all the information that you need. For a software PM role, you should familiarize yourself with some of the common statistics from the software industry.

Smartphone ownership — 20% of the world, 60% of USA adults (45% overall)
Cell phone ownership — 90% of US adults (70% overall)
Desktop — 55% US
Laptop — 60% US
Tablet — 6% of the world
Facebook Users: 1.25B
Facebook Annual Revenue: 9B
Twitter Users: 255M
Twitter Revenue: 1B
Google Annual Revenue: 65B
Gmail Users: 500M
Instagram users — 200M
WhatsApp — 500 million users
Evernote — 100M users (5% of whom are paying customers)

Business Case Questions

• How would you react if a competitor entered your market?
• Should Google charge for gmail access?
• How much should Amazon charge for the Kindle HD?

These are some examples of the business case question. Popular books such as Case in Point and Case Interview secrets walk you through the entire process. Note that these books are geared towards the consulting case interview questions which though similar are slightly different from the PM case interview questions. The difference is that in the consulting interview, as you delve into the problem, you will be given additional data and asked to figure out the problem, which will test your quantitative and analytical skills. In the PM interview, it’s more about the approach that you adopt to crack the case. I used the first book and found it quite useful and there are plenty of practice cases that you can find online. Victor Cheng who is the author of “Case Interview Secrets” has an set of free video tutorials that were quite useful to me.

The Product Question

• How would you design an alarm clock for the blind?
• What is your favourite product and why?
• How would you improve Google Maps?

The product question is a perennial favourite of interviewers and is designed to test out one of the core requirements of a PM i.e a good product sense. If you are interviewing with a company that makes a product for consumers, expect to get questions on its design and how it can be improved. Surprisingly, I had a lot of trouble finding good resources for this question online. There were a few blog posts that I found useful, but most of the resources online were too brief. I eventually came across this framework on Jackie Bavaro’s quora blog that persuaded me to buy the book that she co-authored — Cracking the PM Interview — Gayle McDowell and Jackie Bavaro. This book is more than just interview prep, it introduces you to the PM role and is a great way to get up to speed if you do not have to time to read through all the resources that I linked to in my previous posts (See here and here). She covers all the different categories of questions that you are likely to encounter and my only complaint with the book is that I wished that there were more cases available for practise. Hence, I also ended up purchasing Decode and Conquer — Lewis Lin mainly to have a few more cases to practice. This book focusses more on the interview prep and is thus an excellent complement to the first book. I don’t really see them as competitors, and I recommend buying them both.

Technical/Programming Questions

You are probably not going to be asked to implement an algorithm to detect loops in a linked list on a whiteboard but you do want to research the company you are interviewing with to be sure. Companies such as Google and Facebook do have a programming round, but apparently this has been relaxed recently. You probably should be comfortable answering high level questions about the architecture of the applications that you worked on. If you have a programming background, you should be comfortable answering questions about the projects that you were involved with. It’s worth taking a day or so and trying to remember the details of your projects (tools used, problems faced etc) and writing them down. Some interviewers will drill down into the minute details and you will want to be prepared. Amazon is famous for this type of approach, where the entire interview is about a single accomplishment on your resume.

Behavioral Questions

• Walk me through your resume.
• Why do you want to be a PM here?
• What is your biggest weakness?

You should expect all the usual behavioral questions. It’s easy to underestimate this portion of the interview and most candidates tend to focus their preparation on the other portions of the interview, but most interviewers want to see a cultural fit. Hence, you should have prepared answers for all these questions and they should be tweaked to fit the culture of the company that you are interviewing at. Again, there is no lack of information online on how to tackle these questions. In general, the STAR framework (Situation, Task, Action, Result) tends to work well.

Final Words

As always the key is doing well is to practice as much as possible. If you are unsuccessful during the interview, try hard to get some actionable feedback from the company which you can then use to improve for future interviews. One of my complaints about the interview process is that you can get really good at interviewing by practicing and I am skeptical that this is a accurate predictor of your on the job performance. When I was interviewing for programming jobs, I was terrible during my first interview but improved steadily afterwards and finally ended up getting a job from the fourth company that I interviewed with. I am fairly certain that had I interviewed in the reverse order, I would have worked for Qualcomm rather than Riverbed Technology.