Google Analytics is suming every entry up to your web page, also the ones which are carried out by robots. How you know robot, it program which isn't using the web browser.
However using Severso is collecting the Severso code given from the web browser of the guest. The difference in results demonstrated in the number of the visit by Google Analytics and Severso result from the fact that Severso isn't suming visits of robots up.
In all cases well-known to us Severso results are showing the low figure of visits than Google Analytics. In case of other applications monitoring the www website traffic we don't have such a precise knowledge.
Severso Clients