How to implement competent statistics for the site?

Question

PHP

Hello. Here is the statistics of user views. Everything flies all the buzz. Here is 1 problem left ..
It is necessary to determine from where the user came from (I think to use the referrer)
Thank you in advance for the help

Answer 1

$ref = urldecode($HTTP_REFERER);
or rather liveinternet/Y.metrika/GA )

Answer 2

again this tongue-tied