You have to know the limitations of the approach you are using.<p>Also about session cookies, there is no correlation created if the A&#x2F;B test behavior is tied to the session.  The downside is that different users get different behaviors on different days.  This may be a bad user experience.  The upside is that it is quick and simple for things like landing pages.<p>In the end there is no solution that avoids actually understanding what your data really says.