Reading popularity and difficulty without fooling yourself

Both numbers are estimates. This is what they are made of and when to distrust them.

Where popularity comes from

Play publishes no search volume. Popularity is built from autocomplete: does the term get suggested, for how short a seed, at which position, and how many longer phrases start with it. A term suggested first when the user has typed three letters is popular; a term suggested only when the user has typed almost all of it is not.

Competition adds a little: many apps ranking for a term means people search it. When Play shows an exact-match page with only a handful of results, that is a known name, not an empty market.

Where difficulty comes from

Difficulty is the weight of the apps already in the first ten results: their ratings counts, ratings, install bands, and whether the term is in their titles. It cannot be computed until those apps' listings have been read. An honest tool shows a blank rather than a low number built from missing data, because a blank does not send you after the hardest term in the category.

Reading them together

High popularity and low difficulty for a term relevant to your app is the target. High popularity and high difficulty is a long-term goal, reached through long-tail wins. Low popularity and low difficulty is fine for a new app as long as the term is relevant. Low popularity and high difficulty is not worth a slot in the pool.

Signs you should distrust a number

A popularity that only changed because you added more keywords. A difficulty for a term whose top apps you have never seen fetched. A term you added by hand that shows a low popularity before any suggestion probe ran. In each case the number reflects the tool's data, not the market.