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