Chapter 2 of 4
Scenarios and User Simulation
How to use scenarios as stories that inspire, validate, and guide your engineering decisions.
Key Insights
Scenarios are the bridge between user needs and engineering implementation — they turn abstract requirements into concrete stories.
Simulating user interactions before building helps you catch usability issues and missing edge cases early.
Good scenarios capture motivation, persona, and simulation in a single narrative.
Notes
Scenarios as Stories That Inspire
A scenario is a short narrative that describes a user trying to accomplish a goal with your product. It includes who the user is (persona), what they're trying to do (motivation), and how they interact with the system (simulation). Good scenarios make abstract product requirements feel real and testable.
The Three Parts of a Scenario
Every effective scenario has three components: (1) A Motivation — why is the user here? (2) A Persona — who is this user, what's their context? (3) A Simulation — step by step, what happens? This structure forces you to think through the complete user journey, not just the happy path.
Scenarios That Validate Features
Before building a feature, write 3-5 scenarios for it. If you can't write compelling scenarios, the feature may not be well understood yet. Scenarios that highlight product gaps, frictionful experiences, or surprising user behaviors are the most valuable — they reveal what you don't know.
The First Attempt Without Scenarios
The book describes a case study where a team built a feature without scenarios. The result was technically sound but missed key user needs — the team had optimized for the wrong things. A second attempt, guided by user scenarios, led to a fundamentally different and more successful design.
Quotes
“This book condenses the skills necessary for good-enough-for-now decisions.”
“Whether you're building consumer products, tools for professionals, or internal platforms, understanding your users changes everything.”