---
title: "Extrapolation — USA"
description: "Scaling the observed sample of devices up to population-level visit estimates, so counts reflect real-world volume rather than sample size."
slug: "/docs/datasets/usa/methodology/extrapolation"
last_updated: "2026-08-31"
related_to: ["home-and-work"]
tags: ["methodology", "extrapolation", "usa"]
country: "USA"
applies_to: ["gps", "telco"]
---


# Extrapolation

Only a fraction of the population is observed, so the counts are scaled up to represent the full population. How the scaling factor is derived depends on the signal: it can come from an observed market share (devices relative to population) or be applied to a model's output and calibrated against a population baseline. Either way the goal is the same, output that reflects real-world visit volume rather than the size of the underlying sample.

Applies in USA because it is served by a gps or telco signal. See [Signal](/docs/datasets/usa/supply.md).

## Related

- [Home & work inference](/docs/datasets/usa/methodology/home-and-work.md) — Estimating the likely home and work areas of visitor groups, always at area level and never an address, to enable resident / worker / visitor breakdowns, trade areas, and visitor-only scoping for Visit Length.