{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T10:06:08Z","timestamp":1770977168403,"version":"3.50.1"},"reference-count":49,"publisher":"Association for Computing Machinery (ACM)","issue":"2","license":[{"start":{"date-parts":[[2011,4,1]],"date-time":"2011-04-01T00:00:00Z","timestamp":1301616000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.acm.org\/publications\/policies\/copyright_policy#Background"}],"funder":[{"DOI":"10.13039\/501100002920","name":"Research Grants Council, University Grants Committee, Hong Kong","doi-asserted-by":"publisher","award":["CUHK4154\/10ECUHK4152\/10E"],"award-info":[{"award-number":["CUHK4154\/10ECUHK4152\/10E"]}],"id":[{"id":"10.13039\/501100002920","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["dl.acm.org"],"crossmark-restriction":true},"short-container-title":["ACM Trans. Inf. Syst."],"published-print":{"date-parts":[[2011,4]]},"abstract":"<jats:p>\n            Due to their potential commercial value and the associated great research challenges,\n            <jats:italic>recommender systems<\/jats:italic>\n            have been extensively studied by both academia and industry recently. However, the data sparsity problem of the involved user-item matrix seriously affects the recommendation quality. Many existing approaches to recommender systems cannot easily deal with users who have made very few ratings. In view of the exponential growth of information generated by online users, social contextual information analysis is becoming important for many Web applications. In this article, we propose a factor analysis approach based on probabilistic matrix factorization to alleviate the data sparsity and poor prediction accuracy problems by incorporating social contextual information, such as social networks and social tags. The complexity analysis indicates that our approach can be applied to very large datasets since it scales linearly with the number of observations. Moreover, the experimental results show that our method performs much better than the state-of-the-art approaches, especially in the circumstance that users have made few ratings.\n          <\/jats:p>","DOI":"10.1145\/1961209.1961212","type":"journal-article","created":{"date-parts":[[2011,5,3]],"date-time":"2011-05-03T12:48:53Z","timestamp":1304426933000},"page":"1-23","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":132,"title":["Improving Recommender Systems by Incorporating Social Contextual Information"],"prefix":"10.1145","volume":"29","author":[{"given":"Hao","family":"Ma","sequence":"first","affiliation":[{"name":"The Chinese University of Hong Kong"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tom Chao","family":"Zhou","sequence":"additional","affiliation":[{"name":"The Chinese University of Hong Kong"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael R.","family":"Lyu","sequence":"additional","affiliation":[{"name":"The Chinese University of Hong Kong"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irwin","family":"King","sequence":"additional","affiliation":[{"name":"The Chinese University of Hong Kong"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"320","published-online":{"date-parts":[[2011,4]]},"reference":[{"key":"e_1_2_1_1_1","doi-asserted-by":"publisher","DOI":"10.1145\/1367497.1367693"},{"key":"e_1_2_1_2_1","volume-title":"Proceedings of International Joint Conferences on Artificial Intelligence (IJCAI&amp;#8217;07)","author":"Bedi P.","unstructured":"<scp> Bedi , P. , Kaur , H. , and Marwaha , S . <\/scp> 2007. Trust based recommender system for semantic web . In Proceedings of International Joint Conferences on Artificial Intelligence (IJCAI&amp;#8217;07) . 2677--2682. <scp>Bedi, P., Kaur, H., and Marwaha, S.<\/scp> 2007. Trust based recommender system for semantic web. In Proceedings of International Joint Conferences on Artificial Intelligence (IJCAI&amp;#8217;07). 2677--2682."},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1145\/1281192.1281206"},{"key":"e_1_2_1_4_1","volume-title":"Proceedings of the 14th Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98)","author":"Breese J. S.","unstructured":"<scp> Breese , J. S. , Heckerman , D. , and Kadie , C . <\/scp> 1998a. Empirical analysis of predictive algorithms for collaborative filtering . In Proceedings of the 14th Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98) . Morgan Kaufmann, San Francisco, CA, 43--52. <scp>Breese, J. S., Heckerman, D., and Kadie, C.<\/scp> 1998a. Empirical analysis of predictive algorithms for collaborative filtering. In Proceedings of the 14th Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98). Morgan Kaufmann, San Francisco, CA, 43--52."},{"key":"e_1_2_1_5_1","volume-title":"Proceedings of the Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98)","author":"Breese J. S.","unstructured":"<scp> Breese , J. S. , Heckerman , D. , and Kadie , C . <\/scp> 1998b. Empirical analysis of predictive algorithms for collaborative filtering . In Proceedings of the Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98) . <scp>Breese, J. S., Heckerman, D., and Kadie, C.<\/scp> 1998b. Empirical analysis of predictive algorithms for collaborative filtering. In Proceedings of the Conference on Uncertainty in Artificial Intelligence (UAI&amp;#8217;98)."},{"key":"e_1_2_1_6_1","doi-asserted-by":"publisher","DOI":"10.1145\/564376.564419"},{"key":"e_1_2_1_7_1","volume-title":"Proceedings of the European Conference on Machine Learning and Knowledge Discovery in Databases Part I (ECMLPKDD&amp;#8217;08)","author":"Cao B.","unstructured":"<scp> Cao , B. , Sun , J.-T. , Wu , J. , Yang , Q. , and Chen , Z . <\/scp> 2008. Learning bidirectional similarity for collaborative filtering . In Proceedings of the European Conference on Machine Learning and Knowledge Discovery in Databases Part I (ECMLPKDD&amp;#8217;08) . 178--194. <scp>Cao, B., Sun, J.-T., Wu, J., Yang, Q., and Chen, Z.<\/scp> 2008. Learning bidirectional similarity for collaborative filtering. In Proceedings of the European Conference on Machine Learning and Knowledge Discovery in Databases Part I (ECMLPKDD&amp;#8217;08). 178--194."},{"key":"e_1_2_1_8_1","doi-asserted-by":"publisher","DOI":"10.1145\/1242572.1242610"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1145\/963770.963776"},{"key":"e_1_2_1_10_1","volume-title":"<\/scp>","author":"Dueck D.","year":"2004","unstructured":"<scp> Dueck , D. and Frey , B . <\/scp> 2004 . Probabilistic sparse matrix factorization. Tech. rep. PSI TR 2004-023. Department of Computer Science, University of Toronto . <scp>Dueck, D. and Frey, B.<\/scp> 2004. Probabilistic sparse matrix factorization. Tech. rep. PSI TR 2004-023. Department of Computer Science, University of Toronto."},{"key":"e_1_2_1_11_1","doi-asserted-by":"publisher","DOI":"10.1145\/1081870.1081879"},{"key":"e_1_2_1_12_1","doi-asserted-by":"publisher","DOI":"10.1145\/988672.988727"},{"key":"e_1_2_1_13_1","doi-asserted-by":"publisher","DOI":"10.1145\/312624.312682"},{"key":"e_1_2_1_14_1","doi-asserted-by":"publisher","DOI":"10.1145\/963770.963772"},{"key":"e_1_2_1_15_1","doi-asserted-by":"publisher","DOI":"10.1145\/1341531.1341558"},{"key":"e_1_2_1_16_1","doi-asserted-by":"publisher","DOI":"10.1145\/860435.860483"},{"key":"e_1_2_1_17_1","doi-asserted-by":"publisher","DOI":"10.1145\/963770.963774"},{"key":"e_1_2_1_18_1","doi-asserted-by":"publisher","DOI":"10.1145\/963770.963775"},{"key":"e_1_2_1_19_1","doi-asserted-by":"publisher","DOI":"10.1145\/1008992.1009051"},{"key":"e_1_2_1_20_1","volume-title":"Proceedings of the International Conference on Computational Intelligence for Modeling Control and Automation (CIMCA).","author":"Kohrs A.","unstructured":"<scp> Kohrs , A. and Merialdo , B . <\/scp> 1999. Clustering for collaborative filtering applications . In Proceedings of the International Conference on Computational Intelligence for Modeling Control and Automation (CIMCA). <scp>Kohrs, A. and Merialdo, B.<\/scp> 1999. Clustering for collaborative filtering applications. In Proceedings of the International Conference on Computational Intelligence for Modeling Control and Automation (CIMCA)."},{"key":"e_1_2_1_21_1","doi-asserted-by":"publisher","DOI":"10.1145\/1367497.1367562"},{"key":"e_1_2_1_22_1","doi-asserted-by":"publisher","DOI":"10.1145\/1401890.1401944"},{"key":"e_1_2_1_23_1","volume-title":"Proceedings of the KDD Cup and Workshop.","author":"Kurucz M.","unstructured":"<scp> Kurucz , M. , Benczur , A. A. , and Csalogany , K . <\/scp> 2007. Methods for large scale svd with missing values . In Proceedings of the KDD Cup and Workshop. <scp>Kurucz, M., Benczur, A. A., and Csalogany, K.<\/scp> 2007. Methods for large scale svd with missing values. In Proceedings of the KDD Cup and Workshop."},{"key":"e_1_2_1_24_1","volume-title":"<\/scp>","author":"Lee D. D.","year":"1999","unstructured":"<scp> Lee , D. D. and Seung , H. S . <\/scp> 1999 . Learning the parts of objects by non-negative matrix factorization. Nature 401, 6755, 788--791. <scp>Lee, D. D. and Seung, H. S.<\/scp> 1999. Learning the parts of objects by non-negative matrix factorization. Nature 401, 6755, 788--791."},{"key":"e_1_2_1_25_1","doi-asserted-by":"publisher","DOI":"10.1145\/1367497.1367589"},{"key":"e_1_2_1_26_1","doi-asserted-by":"publisher","DOI":"10.1109\/MIC.2003.1167344"},{"key":"e_1_2_1_27_1","doi-asserted-by":"publisher","DOI":"10.1145\/1143844.1143918"},{"key":"e_1_2_1_28_1","doi-asserted-by":"publisher","DOI":"10.1145\/1277741.1277751"},{"key":"e_1_2_1_29_1","doi-asserted-by":"publisher","DOI":"10.1145\/1458082.1458205"},{"key":"e_1_2_1_30_1","volume-title":"Advances in Neural Information Processing Systems","author":"Marlin B.","unstructured":"<scp> Marlin , B. <\/scp> 2004. Modeling user rating profiles for collaborative filtering . In Advances in Neural Information Processing Systems , Vol. 16 , S. Thrun, L. Saul, and B. Sch&amp;#246;lkopf Eds., MIT Press , Cambridge, MA. <scp>Marlin, B.<\/scp> 2004. Modeling user rating profiles for collaborative filtering. In Advances in Neural Information Processing Systems, Vol.16, S. Thrun, L. Saul, and B. Sch&amp;#246;lkopf Eds., MIT Press, Cambridge, MA."},{"key":"e_1_2_1_31_1","volume-title":"Proceedings of CoopIS\/DOA\/ODBASE Conference. 492--508","author":"Massa P.","unstructured":"<scp> Massa , P. and Avesani , P . <\/scp> 2004. Trust-Aware collaborative filtering for recommender systems . In Proceedings of CoopIS\/DOA\/ODBASE Conference. 492--508 . <scp>Massa, P. and Avesani, P.<\/scp> 2004. Trust-Aware collaborative filtering for recommender systems. 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Roweis Eds., MIT Press, Cambridge, MA, 1721--1728."}],"container-title":["ACM Transactions on Information Systems"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dl.acm.org\/doi\/10.1145\/1961209.1961212","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/dl.acm.org\/doi\/pdf\/10.1145\/1961209.1961212","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,6,18]],"date-time":"2025-06-18T10:59:50Z","timestamp":1750244390000},"score":1,"resource":{"primary":{"URL":"https:\/\/dl.acm.org\/doi\/10.1145\/1961209.1961212"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,4]]},"references-count":49,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2011,4]]}},"alternative-id":["10.1145\/1961209.1961212"],"URL":"https:\/\/doi.org\/10.1145\/1961209.1961212","relation":{},"ISSN":["1046-8188","1558-2868"],"issn-type":[{"value":"1046-8188","type":"print"},{"value":"1558-2868","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011,4]]},"assertion":[{"value":"2009-06-01","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2010-08-01","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2011-04-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}