Shared-vendor crosswalk correlation

measurement

Most platforms resolve IP to location through the same few vendors, so location reports from different platforms are correlated, not independent: cross-platform agreement is not corroboration, and every party can be wrong in the same direction at once. Requested-vs-executed provenance verifies the platform's own conversion step and passes the shared upstream lookup error through untouched.

Detection

Ask each reporting platform which geolocation vendor and database vintage produced its location field; matching vendors means correlated errors.

Mitigation

Never treat multi-platform geographic agreement as independent confirmation when platforms share a lookup vendor
Scope provenance claims explicitly: conversion verified, upstream lookup not
Calibrate against a location signal that does not pass through the shared vendor (GPS-declared impressions, physical delivery points)

Read the full article: IP Lookup To H3 →

Affected conversions

IP lookup → H3 (probabilistic crosswalk) approximate