Definition
This measure counts WordPress plugins that held a place in the top 12,500 plugins at the start of a period. They no longer held one at the end. A departure can mean a plugin's rank fell out of the ranked set. It can also mean the plugin left the WordPress.org directory entirely. Either case is counted as one departure.
Population and window
Rivale measures this across the top 12,500 plugins. The window is the report month. It compares the ranked set at the start of the month against the ranked set at the end. The two dates are the basis for the count.
How it is computed
The ranked set at the start of the period, minus the ranked set at the end. A departure covers both a rank drop out of the set and a removal from the directory. The split between the two is reported from Issue 2.
How to read it
Departures from the top 12,500 plugins reflects the ranked set shrinking on one side. Entries into the top 12,500 plugins reflects it growing on the other. The two figures are best read together for the same period. From a later issue onward, the report splits a rank drop from a directory removal within this same figure. Reading this figure across several months can show whether departures are rising or falling.
What it is not
This measure does not say why a plugin left the ranked set. Before the later split, it does not distinguish a rank drop from an outright removal from the directory. It does not track where a departed plugin's rank went afterward. It only says the plugin is no longer in the top 12,500 plugins at the later date. It is not the same figure as rank stability, which covers movement within the set rather than exit from it.
Related measures
Entries into the top 12,500, Rank stability, New plugin outcomes