Product Manager Interview prep: Product Design

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The Product Design interviews are probably my favorite ones as they allow you to show your full potential. However, if navigated poorly they might become quite the nightmare. So much to think about in such a short amount of time.

From “Design an oven for the blind”, “How would you improve Google Maps?” or “What Amazon Prime should launch next?”, the amount of work to answer these questions correctly can be daunting… or not if you equip yourself with the right frameworks to make sure you answer your question in a structured manner.

When you think about it, the crux of these questions is really about solving a problem for users in a way that will improve an overarching goal aligned with an overarching mission. Depending on where in its life cycle the product is the goal will vary but the mission of the company will most likely remain the same. These are basic yet important strategy aspects that folks like Porter have been hammering since the 80’s. Some notable timeless missions are 3Ms “3M is committed to actively contributing to sustainable development through environmental protection, social responsibility, and economic progress” or Google’s “Organize the world’s information and make it universally accessible and useful”. From this you will see a cascading effect of objectives to help drive that mission forward.

As a Product Manager we want you to demonstrate that you can reconcile the overarching mission through a set of goals aligned with the user’s expectations. The reason for that is simple, if you discard the user from the equation no one will use your product unless you get lucky and if you try to launch a product or feature without linking it to a goal you will be shooting in the dark and somewhat fail to measure success or failure. Another key component, while yes of course users are the top priority, is to remember that you are operating a business or running a business unit so how do you make sure that things you launch don’t hurt your bottom line. Hearing PMs saying that we don’t care about revenue is a bit scary, we do but we want to make sure that we do it while meetings the user’s expectations.

When answering these questions I recommend following this framework to help you progress through the question with your interviewer.

  1. What is our goal?

Ask questions to clarify with your interviewer what is your goal if it is not stated in the question and which constraints you are going to work with. Now remember, you are a business lead so how do you make sure that there is a viable business idea behind it will help you shape sound answers. In the “Oven for the blind” example, everyone would love for these ovens to be free (me first) but unfortunately we can’t create products from thin air and they need money to be manufactured, sold, maintained, supported, replaced, shipped, recycled etc… However there are ways you might be able to reconcile both, for example can governments help with grants to incentive landlords to install them? Everybody wins in a situation like that.

Takeaway: Set a clear objective you’re aiming for with your interviewer. These can be increasing adoption of a product, engagement or revenue. This will give you direction in picking the users that can help you achieve this goal.

2. Who are we building this for?

Now that you have a clear goal, think of which users can help you best drive that goal. This is a crucial part of the question as you will be able to further reduce the complexity of the question. For example if asked “How would you help increase engagement on Spotify?”, in this case let’s assume engagement means “time spent listening”.

Instead of trying to think of a specific user try to replicate in your head all the user journeys that lead to a user listening to a song or podcast on Spotify. This is extremely important! If you can picture an actual user going through the journey you will be able to spot specific actions that you could improve or create if they’re lacking. For example:

Traveler uses Spotify on their smartphone to listen to music/podcasts while on the go → Persona: Traveler> Form Factor: Smartphone> Action: Listen to music/podcasts.

DJ uses Spotify to entertain a wedding on their computer → Persona: DJ > Form Factor: Computer > Action: Play playlists.

Runner uses Spotify to listen to motivational music and podcasts on their Garmin watch → Persona: Runner/Sport enthusiasts > Form factor: Smart watches > Action: Play motivational music or podcasts.

By doing this you’re identifying critical aspects of the user and their journey to pressing the play button. And as you are doing this you are starting to build up aspects of the next phase: What pain points or challenges can we solve for these people?

Before that, pick one of the users above by prioritizing on what is in your opinion the biggest opportunity, this can be through estimating the Total Addressable Market or which user will help you best achieve your goal of increasing time spent listening to content on Spotify.

Takeaway: Instead of doing a laundry list of users, think of user journeys that lead to the desired action defined in the goal. This will allow you to identify critical aspects of the journey and articulate them nicely to your interviewer through the lens of the user. After that pick one user based on their potential to help you best in achieving the defined goal in step 1.

3. What are their pain points and challenges?

This is where the fun starts, now that you have a target user base and you already identified a few journey they go through, now it’s time for you to think of what are the pain points they are encountering today which prevents them from completing the task you’re trying to improve/optimize.

In our previous section we identified the sports enthusiast who uses their smart watch to listen to content while running, walking, lifting weights, kayaking etc… Great. Now imagine that person today wants to listen to audio books while at the gym but don’t want to have to carry around their phone (I feel the pain as I write this). This is a pain point for that user cohort. Try to come up with about 3–4 pain points, prioritize them by potential to best impact your overarching objective and move to solutions.

Takeaway: At this stage identify pain points encountered by users in the journey you went through in step 2. Prioritize the challenge you want to solve based on the potential to hit your goal.

4. What solutions would help solve these pain points?

Almost there :)

At this stage you should have everything you need to think of solutions that can help address your user need. Now remember, this is where your technical skills will be tested as well. For example if you decide to launch audio books in smart watches, try to think if that is technically feasible. What is the average storage available on a Garmin watch? What is the average size of an audio book?

As you write down a few ideas, outline your thought process to your interviewer. Prioritize your ideas by potential to hit your goal, cost and ease of implementation. Also don’t be scared to be creative and shoot big, it is ok to say that you want Spotify to launch their own line of smartwatches in collaboration with Fitbit so they can optimize the media platform for their user (increased storate, better battery life, better bluetooth etc…). However explain to your interviewer why this would be a great or terrible idea.

Takeaway: Your pain points/challenges allow you to identify ideas quickly to help solve them. These pain points are already in line with your objective so think of ideas that can help best impact it. Also, don’t be scared to be bold as long as you keep your interviewer aware that you are pitching an outlandish idea.

5. How should we measure success?

Crucially important, PMs are the voice of the user but also the guardians of the metrics galaxy! This is what is going to help you measure the success of your product. We don’t want PMs optimizing for launches, this leads to sometimes terrible products. At this stage identify 1 North Star metric and 2–3 guard rail metrics. Think about it this way, if you had ONE slide to present to your VPs once a month or quarter to update them on the progress of your product or feature what would these metrics be?

For example say your audio books for smartwatches is super successful in increasing “Listen time” on the platform, make sure this didn’t come at the expense of another aspect of the platform or identify if it brought something else with it. This can be “are now users spending less time” curating playlists, how did that impact podcasts? Or in a positive manner, has this helped us drive new subscribers on the platform as this is a unique feature competitors are not offering today?

Takeaway: Your metrics should allow you to identify if you’ve achieved your goals and also didn’t hurt or helped improve other important metrics. List 1 North star and 2–3 guard rails metrics that you would present quarterly in one slide to your VPs.

If you’ve made it this far, congratulations! You can start exercising this mental framework by finding questions online. I would recommend using the website and Lewis C. Lin’s book which contains a bunch of questions and answers to help you prep your interviews. Lewis has written great content over the years and the framework above is largely inspired by his work on the CIRCLES method.

Also try to do mock interviews with folks as much as possible to help you train your muscle memory. Stellarpeers has a great community to help you find buddies to train with. If you are unable to find people for some reason, record yourself through audio or video to capture where you ramble, stumble etc… and iterate to make sure you progress in the right direction.

You can also find a collection of resources to help you prep in this article I published.

Coming next: The analytics question. Subscribe to receive a notification when it goes online.

— Darbi

Product Manager in the tech industry. Here to help you elevate your PM career!

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