臺大管理論叢 NTU Management Review VOL.28 NO.3

101 NTU Management Review Vol. 28 No. 3 Dec. 2018 recommender system. If so, the ICE technique proposed by this study can be adapted to support this kind of application. Second, because users tend to browse product information before purchasing, the findings of this study can be extended to recommendations of physical products as well. Third, our recommendation approach improves the effectiveness of keyword advertising. The effectiveness of keyword advertising is usually constrained by limitations in the number of related keywords. The ICE approach could also be implemented to expand the array of keywords related to the advertisements in order to provide more personalized advertisement broadcasting services to enhance the attractiveness of advertising (Chou and Lien, 2012). Our study has several limitations which suggest directions for future research. First, the number of articles activated by different concepts was limited by the number of documents in our experimental system. The size of the document collection might be considered insufficient since the limited number of recommended documents might lower the degree of user satisfaction with the recommendation quality. Thus, a sufficient number of documents covering a wider range of concepts may further enhance the coverage of the recommendations. Second, the ACM CCS classification adopted in this study may constrain the application domain of the ICE technique; that is, it can be applied to the recommendation of computer science-related documents only. Hence, how to automatically extend or construct the semantic relationships (i.e., concept heterarchy) to broaden the application domain of the ICE technique may serve as an important research focus in a future study. Furthermore, users’ interests may change over time, so user profiles must be updated continuously in order to enhance the performance of the recommender system. Since this study adopted a laboratory experiment to learn users’ interests, it has a limited ability to test user behavior over the long term. Implementing the ICE technique in commercial websites will be a valid means by which to test external validity in the future.