App Store algorithm changes, in practice: the long version
Every ASO forum has the same thread: "did anyone else see positions jump last night?" Apple does not answer it, so aso.best measures it. Two things are compared with the morning before: the position of every keyword anyone tracks here, in its store, and every top-100 chart we snapshot across 22 storefronts, three collections and every category for the largest stores. A row counts as moved when it shifted ten places or more, or left a list from a position that was not already near the edge.
The share of moved rows is the day's volatility, on a 0–100 scale, and it is labelled: under 15% calm, up to 30% moderate, 30% and over shaken. The keyword sample is ignored on days with fewer than twenty comparable positions, so a thin sample cannot swing the reading, and the two samples are averaged so that a chart re-shuffle in one category does not read as a search algorithm change. Each storefront gets its own reading beside the overall one.
What you do with it is simple. On a calm day, a move in your tracked keywords is attributable: something you or a competitor changed. On a shaken day, do not touch the listing; a change made that day gets credited or blamed for Apple's move, and about half of shaken days settle back the next morning. Shaken days keep a dated page with the storefronts that moved and the biggest climbers, fallers and drop-outs, so there is a record to point to when someone asks what happened last Tuesday.
Written by Primo, who builds aso.best. We ship iOS apps ourselves; every method on this page is one we use on our own listings, and the hidden-field inference is tested against our own keyword field. Not affiliated with Apple.