Rank tracking

Rank is not modelled, it is read: the search is performed and the app is located in the result list. Because the App Store returns at most 200 results for a query, not being in the list means “outside the top 200”, not “no rank”.

Measurement is always per country. The same phrase in two storefronts is two different searches with different result lists and different rivals, which is why tracked keywords are counted as phrase × storefront.

The most critical behaviour in a rank tracker is not writing down a day it could not measure. Store throttling can arrive as an empty body, and a system that records that tells everybody they fell out of the top 200 on the same day.