How does piwik count visits if using anonymous ip

we are using the piwik import script ( to import apache logs into piwik database. Due to security reasons the log entries do not contain the ip addresses from where the request comes (only Our question is how piwik counts the number of vists and if we can trust the calculated visits.
Thanks for your advise in advance.

It is possible the realiability of tracking visits will not be as good when all IPs are set to 0 but in general it should still behave quite correctly. What kind of results do you see?

Hi Matt,
what makes us a little bit insecure is the relation for example between page views and visitors.
In a specific period piwiks shows the following values:
page views: 3357146
unique pages views: 1439351
visitors: 19358
actions per visit: 278
The number of page views seems to be reasonable. 278 actions per visit and about 74 page views per views seems to be a lot. That is why I was asking how does PIWIK counts vists if ip address is always 0 in the log entries.