Index size calculation

I'm confused. I've looked at two different set of equations for calculating index sizes, the one in the Oracle Administrators Guide and the one in Loney's DBA Handbooks. Oracle claims that the ROWID is stored within the index and therefore it's size must be included in the amount of space needed per row. Loney makes no mention of this.

Does anybody know which set of equations yields more accurate results?

-- 
R. Matthew Adams
adamsm_at_source.asset.com    speaking for himself
When someone says, "I want a programming language in which I need only 
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