How D2TR measures Google Discover

What the volatility index measures

The volatility index measures how much today's Google Discover feed differs from its usual pattern over the previous roughly 30 days. It compares three factors with that baseline: new publishers entering the feed, shifts in how impressions are spread across domains, and shifts between material formats. New publisher entry has the largest weight.

The current index, historical view and supporting market signals are available in the Google Discover Updates tracker.

How the relative scale works

Each market is normalized against its own typical variation, so the 0–10 scale is relative. A value around 3 describes an ordinary day, 5–6 is elevated, and 7 or higher is anomalous and may indicate an unannounced Discover update.

Discover changes can roll out unevenly across countries. The same day may therefore look calm in one market and anomalous in another.

Coverage and refresh cadence

The underlying Discover feed is collected continuously, and the indexes are recomputed roughly once an hour. Values for the current day and current three-hour window continue to refine as new observations arrive. Older days can be blank when there is not enough preceding history to judge how unusual they are.

D2TR analytics are derived from publicly observable signals, including public Discover-style feeds, publisher websites, publisher sitemaps and feeds, public news indexes and public interest signals. The public Discover signals API documentation explains how to read the available volatility data.

Estimated metrics and limitations

D2TR analytics, estimated metrics and forecasts are inferential, statistical and analytical outputs built from openly accessible references. They are not a copy, mirror or substitute for a third-party service, search-engine output or content product. Estimated reach should therefore be read as an analytical estimate.

This page describes the measurement approach at a useful public level. The detailed processes used to observe, normalize, deduplicate, classify, weight, score, forecast and present the analytics remain proprietary. See the Google Discover analytics overview for the product context in which these metrics appear.

Questions about the data

For questions about a market, metric or signal, contact the D2TR team. Include the route, market and metric you are reviewing so the question can be assessed in context.