I checked the source publication and the following paragraph describes how they chose the apps:
Since iTunes does not support direct searches for free ap-
plications, we rely on apptrakr.com [2] to provide a contin-
uously updated list of popular, free iOS applications. Once
a new application is added to their listings, our system au-
tomatically downloads the application via iTunes and de-
crypts it. Subsequently, the application is analyzed with
PiOS.
I didn't see anything that described how they chose the Cydia apps however. I bring this up because there are numerous very popular Cydia apps that are simply iOS tweaks that adjust a piece of the interface or something similar. These apps would intuitively be less likely to require any sort of user information at all, so I'm not sure how much I trust these results.
Slashdot Mirror
Since iTunes does not support direct searches for free ap- plications, we rely on apptrakr.com [2] to provide a contin- uously updated list of popular, free iOS applications. Once a new application is added to their listings, our system au- tomatically downloads the application via iTunes and de- crypts it. Subsequently, the application is analyzed with PiOS.
I didn't see anything that described how they chose the Cydia apps however. I bring this up because there are numerous very popular Cydia apps that are simply iOS tweaks that adjust a piece of the interface or something similar. These apps would intuitively be less likely to require any sort of user information at all, so I'm not sure how much I trust these results.