Manual:$wgActiveUserDays/zh

注释
在一段时间中有编辑的用户将被视为活跃用户. 换句话说，如果某一用户在这段时间内没有进行编辑，这位用户将被认为为不活跃. 将会影响在Special:Statistics、Special:ActiveUsers和在维基文本的魔术字 中的数字.

You might want to leave this as the default value, to provide comparable numbers between different wikis.

Old version
A variable with the same name was present from version 1.13.0 to 1.15.x. The description was:

This, along with define what User::isActiveEditor considers to be an active editor. Simply: if a user makes at least X edits in at least Y days, the user is considered active. By default, it's set to 30/30, so 1 edit/day.

This was never actually used.