Jorge Luis Borges imagined an empire whose cartographers drew a map so detailed it was the same size as the empire itself. It was, of course, useless. A map’s value lies in what it leaves out. Drop the irrelevant streets and the unchanged fields, and what remains becomes visible.
Every model you build is a map. A linear regression draws one straight line through a cloud of points and declares, “this is the relationship.” The cloud disagrees at every point. That disagreement, the residuals, is the honest price of simplification. The danger arrives when you forget the residuals exist, when you treat the line as the territory.
The best practitioners hold two truths at once: the model is useful and the model is wrong. The gap between the line and the dots is where humility lives.
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