How do I find out how many people use a particular PPA.
I see on a particular PPA ;
Package build summary
A total of 108 builds have been dispatched for this PPA.
Completed builds
108 successful
0 failed
Does that mean only 108 people have added this PPA to their sources list and installed the package?
This has been a long-standing request and is available if you know about the Launchpad WebService API. This may be available via the standard launchpad webpages but as yet has not been implemented.
source
Linked Blog:
No, that means it has built (compiled and packaged) its packages 108 times.
There's no logging in Launchpad that lets you know how many times a package has been downloaded. At least not logging that is publically available.
The popularity contest package included with Ubuntu tracks usage of packages (if the user agrees). If you know the name of a package that is only present in your PPA, you should find this on their website.