The event data may, for example, evidence user affinities for {HEAD ~ particular items} represented in an electronic catalog, such as book titles, music titles, movie titles, and other types of {TAIL ~ items} that tend to reflect the traits of users 
The event data may , for example , evidence user affinities for { HEAD ~ particular items } represented in an electronic catalog , such as book titles , music titles , movie titles , and other types of { TAIL ~ items } that tend to reflect the traits of users
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH