B. THE PRIVACY CONCERN AND PPDM
Despite that the information discovered by data mining can
be very valuable to many applications, people have shown
increasing concern about the other side of the coin, namely the
privacy threats posed by data mining [2]. Individual's privacy
may be violated due to the unauthorized access to personal
data, the undesired discovery of one's embarrassing information,
the use of personal data for purposes other than the one
for which data has been collected, etc. For instance, the U.S.
retailer Target once received complaints from a customer who
was angry that Target sent coupons for baby clothes to his
teenager daughter.1 However, itwas true that the daughterwas
pregnant at that time, and Target correctly inferred the fact by
mining its customer data. From this story, we can see that the
conict between data mining and privacy security does exist.