Meta replaced Nielsen DMA targeting with Comscore Markets in automotive model ads this June. Warnings started at feed ingestion on April 20; on June 22, campaigns still carrying Nielsen codes stopped delivering. The field changed shape as well as value: a single numeric code (501) became an array of string IDs (["2001"]).
Meta scoped the change to automotive model ads, so far. But a panel or a holdout design keyed to DMA codes now has two options. Re-key to Comscore and repeat the exercise the next time a platform switches vendors, or key to a grid once. This guide shows the grid path.
How the conversion works
H3 is an open hexagonal grid. Every point on earth falls in exactly one cell, nobody licenses the map, and no vendor can renumber it.
Each market in your panel becomes a population-weighted set of cells, and every conversion carries a coverage score that says how faithfully the cells reproduce the market boundary. Your holdout assignment re-expresses on the cell key. The Comscore Market mapping then generates from the same cells, so DMA history and Comscore delivery reconcile through one substrate instead of through each other.
What you do not have to change
Postal-keyed sales files and county-level panels join as they are. Each administrative unit maps to its own weighted set of cells, so the join runs on the cell key and the weights carry the allocation. Platforms keep their native encodings: market IDs, postal codes, circles, polygons. You convert outward at activation and inward at reporting, and the panel never gets re-keyed again.
The grain
We run the conversion at resolution 8, cells of roughly 0.7 km², fine enough to separate one trade area from the next. US state privacy law draws its precise-geolocation line at a radius of 1,750 to 1,850 feet, which falls between resolution 8 and the coarser resolution 7, so the resolution you keep is also a privacy posture: pick it deliberately.
What to do now
Take the DMA definitions your panel uses today and materialize them as weighted cell sets, storing the coverage score alongside each cell set. Re-express your holdout assignment on the cell key. Then generate the Comscore mapping from the same cell sets rather than from the old DMA codes.
The full proposal, including the temporal half and the activation paths per platform, is the 168 Grid.
Tell us the geographies your panel is keyed to and we will scope the conversion with you. The tools to run it yourself follow.
