On Tue, Nov 19, 2002 at 09:54:13AM -0600, Bob Apthorpe wrote: > > What does "joint and conditional frequency analysis" mean? > > First, start with Larry Gonick's fantastic "The Cartoon Guide To Statistics": > http://www.powells.com/cgi-bin/biblio?inkey=7-0062731025-0 > > Being neither a mathematician nor a statistician, sounds like joint > frequency analysis is how you derive P(A and B), and conditional frequency > analysis is how you generate P(A given B) (generally written P(A|B)), > where A and B are two events (in this case, the occurrence of words A and > B, respectively.) Bayes' Theorem boils down to P(A|B) = P(A and B)/P(B), which > is intuitive if you draw the big Venn diagram.
Very good analysis! My probability professor would be proud of that explanation. The only gripe I have is with your definition of Bayes's theorem. The really controversial point about Bayes's work was his work after the derivation you suggested above (strictly speaking, P(A|B)=P(A&B)/P(B) is just the formula for conditional density - ie, A given B). Bayes went on to model how confident you could be of the decision resulting from the probability calculations. AI people aparantly love the idea - mathematical philosophers hate it because it's a subjective measurement. In this case it doesn't really matter since we have a rigorous definition for the confidence (determined by the spam/non-spam corpus). -- Ross Vandegrift [EMAIL PROTECTED] A Pope has a Water Cannon. It is a Water Cannon. He fires Holy-Water from it. It is a Holy-Water Cannon. He Blesses it. It is a Holy Holy-Water Cannon. He Blesses the Hell out of it. It is a Wholly Holy Holy-Water Cannon. He has it pierced. It is a Holey Wholly Holy Holy-Water Cannon. He makes it official. It is a Cannon Holey Wholly Holy Holy-Water Cannon. Batman and Robin arrive. He shoots them. ------------------------------------------------------- This sf.net email is sponsored by: To learn the basics of securing your web site with SSL, click here to get a FREE TRIAL of a Thawte Server Certificate: http://www.gothawte.com/rd524.html _______________________________________________ Spamassassin-talk mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/spamassassin-talk
