This is the single most common misreading of the Heatmaps table, so it gets its own page. The table holds two kinds of row, and Whose activity switches between them.
| Identified users | Anonymous visitors | |
|---|---|---|
A row is | One person | One browser profile |
Same human, two devices | One row | Two rows |
Has contact info | Yes | Never |
Answers | Who is using the product | How much traffic is unidentified |
Because the two kinds of row count different units, identified + anonymous is not your total audience and the ratio between them is not an identification rate. The count with Everyone selected mixes people and browsers for the same reason. Compare identified users against themselves over time, and anonymous visitors against themselves.
Windows, Not Totals
The table reads a window of recent data rather than your whole history. Each site returns up to 5,000 identified users and 5,000 anonymous visitors, most recently active first, and the per-person facets — events, pages, device, country — are computed from that site's most recent 20,000 events in the selected range.
Over a long range on a busy site, older rows will have no event data attached. Those rows cannot be classified by engagement, pages, device or country. When that happens, a line above the table says which date the counting starts from. Shorter ranges are complete.
If the table looks oddly sparse, narrow the date range before assuming data is missing. A 7-day window on a busy site is complete where All time can be a sample.