If any statistic information is saved these are saved with identifiers that cannot be traced back to any user. Users email adresses, contacts, phone numbers or any identifiable information never leave the applications. I dont send spam, and I dont want to invite your friends.
Analysis of app usage
For some apps we use https://fabric.io Crashlytics. This provides me with errors caught in the wild so that I can pro-actively fix stuff that doesnt work as intented.