Link-Based Methods for Web Information Retrieval Clive Nettey Abstract: Although commercial search engine companies have reported a great deal of success in appropriating link-based methods, these methods have struggled to demonstrate significant performance improvements over content-only retrieval methods in several off-line Web IR evaluations. In this thesis the effectiveness of link-based methods is assessed against content-only retrieval baselines. Algorithms embodying established HITS, in-degree, realised in-degree, and sibling score propagation techniques are evaluated alongside variants of those algorithms. The variant algorithms are devised to aid in three secondary lines of investigation relating to link-based methods: the effects of link randomisation, the utility of sibling relationships and the influence of link densities. All established link-based algorithms are demonstrated to improve on several content-only retrieval baseline performance metrics with the realised in-degree algorithm proving to be particularly effective across all considered metrics. In relation to the other lines of investigation, the experimentation reveals that: leveraging sibling relationships does not lead to significant performance improvements, higher link densities do not afford performance improvements and that algorithms are susceptible to link randomisation. Keywords: Information Retrieval, World Wide Web, Hypertext Algorithms, Web Information Retrieval, Link-based Methodst