Interaction design guidelines found according to your preferences anon Powershot s2 Is Digital Camera[ Ads padm One recommended item ldjut your preferenees to find the right camera for you Manufaeturer xEnon +5JMEol 412 User-initiated unit Flash Memony+ 16MB criti LcD Sereen size Thiel nese 429 weighs 40479 have more matching cameras with the following 1. Less Cpbca Zoom an Thrner and Leter weigrt System-suggested mpound critiques Fig. 2 The DynamicCritiquing interface critique options(as the frequent association rules) will be then produced. For example supposing the occurrence of heavier laptops is highly frequently associated with the occurrence of cheaper prices in the remaining items, a compound critique with the form of ([weight >] [price <l)(i.e, heavier and cheaper)will be generated. Thus, the Dynamic Critiquing agent uses the Apriori algorithm to discover the highest recurring compound critiques representative of a given data set. It then favors those candidates with the lowest support values("support value "refers to the percentage of products that satisfy the critique). Such selection criterion was motivated by the fact that pre- senting critiques with lower support values provides a good balance between their kely applicability to the user and their ability to narrow the search(McCarthy et al 2004a,2005bc) In addition to functioning as critique suggestions, the dynamically generated com pound critiques have been also regarded as explanations exposing the recommendation opportunities that exist in the available products(McCarthy et al. 2004b; Reilly et al 2005). They may help users be familiar with the product domain and understand the relationship among different features within the alternatives. Users can be then stim- ulated to express more preferences or be prevented from making retrieval failures (Reilly et al. 2005) 2.2 K-item user-initiated critiquing Instead of suggesting pre-computed critiques for users to select, the purely user initiated critiquing approach focuses on showing examples and stimulating users to define critiques themselves. It does not limit the size of critiques a user can manip- ulate during each cycle, so that the user can post either unit or compound critiquesInteraction design guidelines 173 One recommended item User-initiated unit critiquing System-suggested compound critiques Fig. 2 The DynamicCritiquing interface critique options (as the frequent association rules) will be then produced. For example, supposing the occurrence of heavier laptops is highly frequently associated with the occurrence of cheaper prices in the remaining items, a compound critique with the form of {[weight >], [price <]} (i.e., heavier and cheaper) will be generated. Thus, the DynamicCritiquing agent uses the Apriori algorithm to discover the highest recurring compound critiques representative of a given data set. It then favors those candidates with the lowest support values (“support value” refers to the percentage of products that satisfy the critique). Such selection criterion was motivated by the fact that pre￾senting critiques with lower support values provides a good balance between their likely applicability to the user and their ability to narrow the search (McCarthy et al. 2004a, 2005b,c). In addition to functioning as critique suggestions, the dynamically generated com￾pound critiques have been also regarded as explanations exposing the recommendation opportunities that exist in the available products (McCarthy et al. 2004b; Reilly et al. 2005). They may help users be familiar with the product domain and understand the relationship among different features within the alternatives. Users can be then stim￾ulated to express more preferences or be prevented from making retrieval failures (Reilly et al. 2005). 2.2 K-item user-initiated critiquing Instead of suggesting pre-computed critiques for users to select, the purely user￾initiated critiquing approach focuses on showing examples and stimulating users to define critiques themselves. It does not limit the size of critiques a user can manip￾ulate during each cycle, so that the user can post either unit or compound critiques 123