Decode and Conquer

Most business decisions start as a vague question. How would you improve this product? What should we charge? Should we enter that market? This book trains one skill: turning a question like that into a short, structured answer you can defend.

The problem it solves

It is written for product management interviews, and says so. The interviewer asks for a design, a number, a price or a strategy, and the candidate rambles, jumps to a solution or cannot stop talking. The book gives a repeatable way to start, to organise the middle and to finish with a recommendation.

What changes in how you work

You stop answering the first question that comes to mind. You ask who the product is for, what they need and which need comes first. You list at least three ideas before you pick one, and you say what is wrong with each. That habit is useful in any meeting where someone asks for your view.

Where it goes beyond interviews

The analytical chapters apply to a normal week in a small company. Estimation, pricing, metrics, trade-offs and new market entry are the questions an owner faces when deciding what to build or sell next. The book warns that a pro and con list feels objective and complete, and says a good answer still commits to one position.

When to read it, and when not to

Read it before an interview, or before you hire someone who will be interviewed on these topics. Skip it if you want a general book on running a product team. It is a collection of questions and model answers, and many examples come from Google, Amazon, LinkedIn and Facebook, around 2013. Some products have changed, but the way of thinking has not.

How it connects to decisions you can log

A good answer in this book ends with a choice, the reasons and the alternatives that lost. That is a decision record in miniature. If you write your own answers down in that shape, you build a log you can look back on, and a pattern of work that someone else can repeat.

The book argues that a product management interview is a skill you can practise, and that sample answers teach it better than tips do. Lewis C. Lin, who coached job seekers for this type of interview, gives a method for each type of question and then a set of worked answers with comments. The second edition covers design, technical, estimation, pricing, metrics, strategy, vision, stress and behavioural questions.

Introduction

Lin says tips and frameworks are easy to find online but real answers are rare, so this book is mostly answers. He also warns that it is not a script. The aim is to prepare you for questions that are not in the book, with sound content and a crisp delivery. He adds that nothing replaces real knowledge of design, business and technology, which a product manager has to build over time.

Chapter 1: "Critiquing Design"

A good critique uses a scorecard. Lin starts from the ten principles of the industrial designer Dieter Rams and suggests you pick no more than three criteria, state them, explain how the product meets them or not, and back it up with evidence and a comparison with similar products. The sample questions ask about LinkedIn's endorse feature, a product you like and a product that was designed badly.

Chapter 2: "Designing a Desktop Application"

This is where the CIRCLES Method™ appears. The steps are comprehend the situation, identify the customer, report the customer's needs, cut through prioritisation, list solutions, evaluate trade-offs and summarise your recommendation. Lin says candidates stumble when they start, ramble, cannot end, or give a solution with no context. For the first step he suggests asking what the product is, who it is for, why they need it and how it works.

The method asks you to pick one persona and describe them, rank their needs with a simple weighted matrix, and brainstorm with techniques such as reversing the situation or challenging the status quo. He recommends at least three ideas, because the first is rarely the best. The worked answer improves Microsoft PowerPoint for salespeople.

Chapters 3 to 6: the other design questions

The next four chapters apply the same method to other things you might be asked to design. They are "Designing a Web page or Website", "Designing a Mobile App", "Designing a Consumer Product" and "Designing a Service or Other Product". Each comes with a tip. Interview visually, and sketch on a whiteboard, because pictures carry ideas better than words. Review common design patterns before you go in. Ask the Five Whys to find problems customers have not put into words.

The tip for the consumer product chapter is the one I would keep. Do not follow a framework blindly. In Lin's words, "Interviewers will react to candidates that sound robotic." He prefers a candidate who sounds like a colleague in a conversation.

Chapter 7: "Getting Technical"

Product managers at some companies are expected to lead engineers, so they are asked technical questions. Lin gives five steps: understand the question, work through a simple base case, talk aloud, write the solution (pseudo code is usually fine) and review it. He also suggests brushing up on sorting algorithms, trees and hash tables. The sample questions include explaining recursion, designing an elevator control system and detecting duplicate websites.

Chapter 8: "Getting Analytical: Estimation"

Lin says estimation questions are not brainteasers. Product managers make judgement calls on numbers all the time, and the interviewer wants to see which assumptions you choose and whether they are sensible. There are two routes. Top down starts with the whole market and narrows to the part you care about. Bottom up starts from one observed data point, such as one store, and scales it up. The questions range from McDonald's revenue to how many elevators a 50-storey building needs.

Chapter 9: "Getting Analytical: Pricing"

The number that matters most is the customer's willingness to pay. For a new category it is tied to what it costs to build. For an existing category it is the competitor's price plus whatever you need to add to match them. The best way to settle a price is to try different ones, as Amazon does. If you cannot, survey customers, but adjust for the fact that surveys give optimistic answers. The questions include pricing the Kindle Fire HD and projecting the financial effect of a cut to the Amazon Prime price.

Chapter 10: "Getting Analytical: Metrics"

Most product teams decide with A/B tests, so interviewers ask which metrics you would watch and what you would do with the results. Lin offers the AARM Metrics™ (acquisition, activation, retention, monetisation) and the Three Loops™ (data, compulsion and viral), which show how retention feeds on itself. His tip on A/B results is useful for any owner. If a feature raises revenue but lowers logins, ask what the company's current objective is and decide on that.

Chapter 11: "Strategizing: Trade-offs"

Pro and con analysis is the most common strategy tool, and it is satisfying because it feels objective and complete. The worked answers argue both for and against display adverts on Amazon. The comments say to be precise, back claims with evidence and commit to a single position. They also say the follow-up question tests whether you can drop your first stance and argue the other side.

Chapter 12: "Strategizing: New Market entry"

Here the book gives a checklist, so the interviewer can agree or disagree with each item. It covers market characteristics (size, growth, margins and trends), the competitive environment (how many competitors, their resources and their strengths) and company fit (expertise, scale, distribution, suppliers and brand). The questions ask you to choose a new category for Amazon, choose between an oven and an oven mitt, and judge a grocery idea.

Chapter 13: "Strategizing: CEO-level Issues"

These questions cover competition, acquisitions, complementary products and corporate values. Lin does not want a framework for each. He suggests working out how the company makes money and what drives it, then asking how the competitor, the acquisition or the new product would move those drivers. The examples are about Google, Quora, Yellow Cab and Uber.

Chapter 14: "Creating Vision"

A vision answer shows that you think big, can influence a team and are credible. A good vision is big but looks doable, like the 1961 pledge to land a person on the moon. The advice is to solve a real, large problem, be unique and memorable, and give the plan for getting there as much air time as the idea itself.

Chapter 15: "Passing the Stress Test"

Some interviewers put you under pressure on purpose, to see whether you waffle or turn defensive. Lin suggests working out why they are doing it (often cultural fit), practising with a friend who plays the tough interviewer, and separating the question from the emotion. The worked answer shows a candidate getting defensive, then stopping, apologising and asking clarifying questions.

Chapter 16: "Winning the Behavioral Interview"

Behavioural questions ask about past work. Lin says hiring managers find them the best predictor of success, so more of them use these questions. Interviewers look for credibility (were you the owner or a participant, and was it a good or a great result) and likability. Lin rejects the STAR method as mechanical. His own DIGS method™ asks you to dramatise the situation, indicate the alternatives, go through what you did and summarise your impact.

What to do with it

• Pick the question type you fear most and read that chapter first, then answer the practice questions out loud before you read the model answers.
• Write each answer down as a decision: the choice, the reasons and the options you turned down.
• Turn the checklists into your own templates, for example for a new market, a price change or a feature test.
• Practise with a friend who interrupts and pushes back, so the pressure feels familiar.
• Keep the structure in your head and the script out of your mouth. Adapt the method to the question you are given.