How this is calculated

The figures on the analytics page. Currency follows the selector. A missing number is left off, not invented.

Change: (current − previous) / previous × 100; If the previous value is missing or zero, the change is shown as 0. It is not treated as infinite.
All collections: The pre-aggregated total for the selected currency; Volume, sales, floor, and average price come from that total, not from re-adding every collection in the browser.
A subset of collections: Volume and sales are sums. Floor and average price are the unweighted mean of the collections that have a value.; A collection with no figure for that currency is left out of the mean. It is not counted as zero.
Floor change on a subset: Same percent change, on the mean of the previous floors; This used to stay at 0. The previous floor was on each collection and was not being averaged.
Daily sparkline: A running sum of the last points in the daily series; Each point is the sum so far, not that day alone.
Monthly sparkline: The last 12 monthly sales counts; These are not a running sum.
Collector and artwork counts: The analytics job, or the catalogue count if that job left the figure empty; The fallback is the number of records, not a sale.