I’m wondering how the number of downloads displayed in the plugin-directory correlates to the number of actual websites using the plug-in.
I realise some people will download and never install and that others might download multiple times, but if a plug-in has been updated 5 times from the WP dashboard are these updates included in the overall download figure too?
That’s the total number of downloads. It includes direct downloads in the Repository and installs/updates done in the dashboard.
Quotes from Otto comments in this 2010 article about the stats charts in every plugin’s page.
From Ipstenu, in this forum thread:
An idea of the total sites using a plugin may be gathered comparing the Changelog and Statistics of a plugin, in this case WordPress SEO by Yoast:
Adding the daily download in the period of time after the plugin has an update until it reaches back its daily download average. And discounting that average daily number from the sum.