Order of Approximation

Order of approximation is the practice of solving problems at the right level of precision for the decision at hand. A zeroth-order approximation ignores all nuance and gives a rough ballpark. A first-order approximation captures the dominant variable. Higher orders add correction terms for smaller effects. The key insight isn't mathematical — it's strategic: most decisions don't require third-order precision, and pursuing it wastes time while the window for action closes. A founder estimating market size doesn't need four decimal places; they need to know whether the opportunity is a $10M market or a $1B market. Getting the order right — knowing how precise to be — is often more valuable than getting the exact number right. The model warns against two failure modes: acting on estimates too rough for the stakes, and paralysis from pursuing precision the decision doesn't require.