Thanks Christian & Mladen for sharing your thoughts, unfortunately they only confirm my thoughts that nobody really knows how this statistic is gathered or used - and based on the large variation in values on the same system, maybe Oracle doesn't even know. I wonder if maybe it's not used at all currently, but just there for use in a future version where perhaps it will be better documented? I guess for now the safest approach is that which you described Chris - gathering stats several times and then taking the average (I'm guessing that's what you meant by "good"?) value. Regards, Brandon Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it. -- //www.freelists.org/webpage/oracle-l