There are two ways to exclude stats :
- First is under the package control and is based on status code. Server and client error are not counted because they do not reflect a real web activity. Redirect are also rejected (status code 300+) because these are redirection and cache activity. Other tools may use the 304 status code (proxy) but this is not a real user request to your server, the proxy just ask if the document is uptodate or not. Using your browser 'reload' button is a easy way to increase this number and so should not be taken into account.
Check the script section to see other status code and help associated.

- Second and last way to reject stats is from your personnal configuration. You may want to exclude some hosts and/or pages from your stats. Also spiders can be excluded if you need it as this is not real users. Spammer is a kind of spamdexing (spamming aimed at search engines). The technique involves making repeated web site requests using a fake referer url that points to the site the spammer wishes to advertise.

Status code Associated Message Meaning
Redirect
301/2
Moved Temporarily
This code is a temporary redirect to a new location. Apparently, many user agents always issue GET requests for the new URI, regardless of the original request method.
304
Not Modified
This code is used when the client makes a conditional GET request (e.g. If-modified-since) and the resource has not changed ... so the document requested is not sent from the server but from the proxy.
Client error
401
Unauthorized
This code is used when access to a resource is protected and the client did not provide valid authentication credentials. Often the 401 response includes information that causes the user agent to prompt the user for a username and password.
403
Forbidden
This code indicates that the resource cannot be accessed, regardless of any authentication credentials. For example, this happens if a directory or file is unreadable due to file permissions.
404
Not Found
This code indicates that the requested resource does not exist on the server. It may also be used in place of 403 if the server doesn't want to acknowledge that the resource exists, but cannot be accessed.