Each creator stands on top of their own stack. A screen shows the video's day-1 VPI: its views on the first day we observed it in Most Popular, divided by the channel's usual views, the median of its own long-form videos published before it. The colour is the IOSA level. Day 1 is the only point every record has, so it is the one we compare on. The measure is age-indexed, not age-adjusted.
The floor is split by usual views. Each zone holds one baseline band, and no figure is ever compared across zones. Getting into Most Popular takes absolute views, so a small channel has to beat its usual views by far more to appear at all. That is why the hottest screens sit in the smallest zones. It comes from the chart's entry threshold, not from the metric.
Screens switched off are videos whose baseline could not be computed. They are valid records without a VPI and they stay in the room. A creator whose videos fall in two bands stands in both zones.
Live streams stay in the room, as they do in the index. Hide live streams takes out the videos flagged as live and rebuilds the zones and their medians without them. The flag is recorded from 4 October: most videos first observed before that carry no flag, so they stay in either way.
Creators whose best video this week reached level 5 (Breakout) raise their arms.
When a video leaves Most Popular, the value IOSA publishes is the highest VPI observed, always with its views and its days in Most Popular. Hover a TV to see both.
Data: IOSA daily reading of YouTube's Most Popular category charts, official YouTube Data API. iosaresearch.org