Is This Worth Doing?
How to Evaluate Profit Before Revenue Exists
Preface
A word before we start, because this book asks a question most entrepreneurship books agree to postpone.
The question is whether the thing you are about to commit to will make money, asked before any money has come in. The standard answer is that you cannot know that yet, so you should build something, put it in front of people, and find out. This book takes a different position: much of it can be known in advance, the methods for finding out are within reach of anyone willing to talk to a few dozen customers, and the reason the question keeps getting postponed has less to do with what is knowable than with who pays for being wrong.
So this is a book about estimating expected profit before revenue exists. You might be deciding whether to launch or walk away, what to charge, whether to buy the business, whether to sign the lease, or whether the growth you are being pushed toward can actually pay for itself. Those decisions look different from one another and they all bottom out in the same arithmetic, and the arithmetic has one unknown in it.
It is worth being equally clear about what this is not. It is not a business plan template, a market-sizing exercise, a fundraising narrative, or another framework for organizing what you already believe. Those exist in quantity, some of them are useful for other purposes, and not one of them estimates how many units you will sell. That number is the whole problem.
The method underneath is ordinary economics put to a use it is not usually put to. You will ask a particular kind of question of a particular group of people, and their answers become a demand curve estimated from evidence rather than assumed from optimism. Set your prices and costs against that curve and you have an expected profit with its assumptions in the open and its fragile points marked. When the answer is that this will not work, you will find that out for the price of a survey rather than the price of a year.
You will not need to code, and you will not need to have taken economics. The arithmetic is handled by companion apps, or by an AI you hand the method to. What neither can do is decide what counts as a customer, ask an honest question, or tell you whether the number it just produced deserves your confidence. That work stays yours, and most of this book is about doing it well.
What I can promise is narrow. Not certainty, which nobody can offer you honestly about a business that does not exist yet. What the method offers is that when you commit, you will know what you are betting on, how much of it you actually checked, and what would have to be true for you to be wrong. That is a smaller claim than the ones you are used to hearing. It is also one I can keep.
Bring a real decision. Something you are facing now, or expect to face soon enough that it makes you uneasy. Read with it in mind, and by the end you will have an estimate of what it is worth, and a clear-eyed account of how much that estimate is worth.
This book is the result of more than two decades of teaching, research, and experimentation around a persistent question: how to make sound economic decisions when the information you wish you had does not yet exist. Earlier versions appeared as course materials, unpublished manuscripts, and prior drafts, under different titles and with different emphases. This is the first time the ideas have been brought together around a single problem, which is how to evaluate whether a business is worth doing when profit must be judged before revenue exists.