Knowing me, knowing you'-using profiles and social networking to improve recommender systems Whereas the benefit of combining opinions in that there is a need for people to create matters of fact is both demonstrable and understood theoretically, the same is not true for matters of taste [18. Simple aggregation of opinions in matters of taste that using a network of existing connections is the raises conceptual difficulties as people are entitled to best way of doing this different opinions on movies, music or restaurants. that making the above easy is a great benefit. Yaniv argues that the most promising strategy to examine these factors in matters of taste would be in While users have various options to find other users considering the personal match between advice-seeker with whom to make connections the main one is still and recommender, assuming that the greater the through the networks of their friends. Other options similarity between them, the greater the impact and usually include some form of database search where benefit of advice received [18]. The argument is interests and demographics can be specified. In therefore not to find optimal solutions, but rather to use networks of potentially thousands of people both these heuristics that simply find good solutions options can be quite cumbersome and do not actually follow the advantages of real-world introductions 2.3.3 Social embedding of recommendations Researchers have pointed out that recommendations In real-world introductions, the person introducing have to be considered in the social context in which they two people usually has a motive for doing so, be it for are delivered [21]. For instance, what kind of occasion is professional or personal reasons. In an on-line social a restaurant recommended for? Is it a business dinner or network, it is easy for users to browse and contact a first date? Who are you going to the cinema with? Are people in their friends,. thus skipping the you buying a CD for yourself or as a present? introduction stage. Further, in the real world, social connections are typically revelatory about the social RSs operate under the assumption that the world status of a person, and seeing someone within the can be described objectively, and that optimal solutions context of their connections is a useful source of to problems can be deduced from these objective information about that person [27] descriptions [22]. Consequently, recommendations om such systems are de-contextualised thus ignoring In an on-line context such as a social networking the situatedness of a recommendation application, the situation is slightly different. Wherea real-world connections carry some significance(because To allow advice-seekers to judge the validity and both parties are tied to their real- world identities an their connection involves some common ground crucial piece of information that should be included in whether personal or professional), the same is not true often be easily altered and thus do not carry the same Situating recommendations in their social context in reliability factor that real-world identities would an on-line environment leads us to examine how people use tools to se on line. Social networkin Thus, an often seen phenomenon in on-line social applications pre networking is that a lot of users sign up and simply grow connect their f a platform for their users to their networks as much as possible. Subsequently, their through their profiles. Seeking network loses value in terms of situating that person recommendations from friends is a naturally occurring within a social circle social process, which has so far been under explored in this context. Section 2. 4 therefore briefly examines social networking application Both the systems and its users have matured in terms of usage and specific usage goals. Through higher broadband Internet proliferation, more users 2.4 Social networking have access to effectively use these communication Social networking applications such as Friendster [23, platforms for a variety of purposes such as dating Facebook [24], hi5[25, and mySpace [26], have grown business networking and sharing of digital content significantly over the past few years. While early systems saw an initially enthusiastic take-up, this was While certain social networking platforms are still followed by an equally quick decline which was mainly completely open(e. g. Friendster), some opt for a semi due to a lack of clearly defined usage goals. Once closed approach(e. g. Facebook ) and others for a closed signed up, users simply did not know what to do with 'by-invitation-only' approach (e. g. Orkut). Open e applications. Donath and boyd point out [27, these networks such as Friendster are able to attract a large networking sites had the three following basic number of users but are also more vulnerable to underlying assumptions BT Technology Journal.Vol 24 No 3. July 2006‘Knowing me, knowing you’ — using profiles and social networking to improve recommender systems BT Technology Journal • Vol 24 No 3 • July 2006 87 Whereas the benefit of combining opinions in matters of fact is both demonstrable and understood theoretically, the same is not true for matters of taste [18]. Simple aggregation of opinions in matters of taste raises conceptual difficulties as people are entitled to different opinions on movies, music or restaurants. Yaniv argues that the most promising strategy to examine these factors in matters of taste would be in considering the personal match between advice-seeker and recommender, assuming that the greater the similarity between them, the greater the impact and benefit of advice received [18]. The argument is therefore not to find optimal solutions, but rather to use heuristics that simply find good solutions. 2.3.3 Social embedding of recommendations Researchers have pointed out that recommendations have to be considered in the social context in which they are delivered [21]. For instance, what kind of occasion is a restaurant recommended for? Is it a business dinner or a first date? Who are you going to the cinema with? Are you buying a CD for yourself or as a present? RSs operate under the assumption that the world can be described objectively, and that optimal solutions to problems can be deduced from these objective descriptions [22]. Consequently, recommendations from such systems are de-contextualised, thus ignoring the situatedness of a recommendation. To allow advice-seekers to judge the validity and appropriateness of a recommendation, situatedness is a crucial piece of information that should be included in an RS. Situating recommendations in their social context in an on-line environment leads us to examine how people use tools to socialise on line. Social networking applications provide a platform for their users to connect their friends through their profiles. Seeking recommendations from friends is a naturally occurring social process, which has so far been under explored in this context. Section 2.4 therefore briefly examines social networking applications. 2.4 Social networking Social networking applications such as Friendster [23], Facebook [24], hi5 [25], and mySpace [26], have grown significantly over the past few years. While early systems saw an initially enthusiastic take-up, this was followed by an equally quick decline, which was mainly due to a lack of clearly defined usage goals. Once signed up, users simply did not know what to do with the applications. Donath and Boyd point out [27], these networking sites had the three following basic underlying assumptions: • that there is a need for people to create connections, • that using a network of existing connections is the best way of doing this, • that making the above easy is a great benefit. While users have various options to find other users with whom to make connections, the main one is still through the networks of their friends. Other options usually include some form of database search where interests and demographics can be specified. In networks of potentially thousands of people both these options can be quite cumbersome and do not actually follow the advantages of real-world introductions. In real-world introductions, the person introducing two people usually has a motive for doing so, be it for professional or personal reasons. In an on-line social network, it is easy for users to browse and contact people in their friends’ networks, thus skipping the introduction stage. Further, in the real world, social connections are typically revelatory about the social status of a person, and seeing someone within the context of their connections is a useful source of information about that person [27]. In an on-line context such as a social networking application, the situation is slightly different. Whereas real-world connections carry some significance (because both parties are tied to their real-world identities and their connection involves some common ground, whether personal or professional), the same is not true for on-line social networking. On-line identities can often be easily altered and thus do not carry the same reliability factor that real-world identities would. Thus, an often seen phenomenon in on-line social networking is that a lot of users sign up and simply grow their networks as much as possible. Subsequently, their network loses value in terms of situating that person within a social circle. Both the systems and its users have matured in terms of usage and specific usage goals. Through higher broadband Internet proliferation, more users have access to effectively use these communication platforms for a variety of purposes such as dating, business networking and sharing of digital content. While certain social networking platforms are still completely open (e.g. Friendster), some opt for a semi￾closed approach (e.g. Facebook), and others for a closed ‘by-invitation-only’ approach (e.g. Orkut). Open networks such as Friendster are able to attract a large number of users, but are also more vulnerable to misuse