http://e26whn2524322mkxb3cbyk27ev2ihhq2biz35hty7gzgsyrwrygq27yd.onion/posts/blog/software-development/designing-privacy-friendly-analytics.html
Conclusion There are, obviously, some sacrifices compared to a traditional analytics system - I can't, for example, track whether a user is a repeat visitor. But, that's very much by design: I'm collecting the stats required to monitor and improve delivery of my content, whilst keeping that information entirely disaccociated from users themselves.