Composite web search

The figure above shows Google’s results page for the query “taylor swift”, captured in March 2016. Assembled around the long-established list of search results is content extracted from various source — news items and tweets merged within the results ranking, images, songs and social media profiles displayed to the right of the ranking, in an interface element that is known as an entity card. Indeed, the entire page seems more like an assembly of content extracted from various sources, rather than just a ranked list of blue links. Search engine result pages have become increasingly diverse over the past few years, with most commercial web search providers responding to user queries with different types of results, merged within a unified page. The primary reason for this diversity on the results page is that the web itself has become more diverse, given the ease with which creating and hosting different types of content on the web is possible today. This thesis investigates the aggregation of web search results retrieved from various document sources (e.g., images, tweets, Wiki pages) within information “objects” to be integrated in the results page assembled in response to user queries. We use the terms “composite objects” or “composite results” to refer to such objects, and throughout this thesis use the terminology of Composite Web Search (e.g., result composition) to distinguish our approach from other methods of aggregating diverse content within a unified results page (e.g., Aggregated Search). In our definition, the aspects that differentiate composite information objects from aggregated search blocks are that composite objects (i) contain results from multiple sources of information, (ii) are specific to a common topic or facet of a topic rather than a grouping of results of the same type, and (iii) are not a uniform ranking of results ordered only by their topical relevance to a query. The most widely used type of composite result in web search today is the entity card. Entity cards have become extremely popular over the past few years, with some informal studies suggesting that entity cards are now shown on the majority of result pages generated by Google. As composite results are used more and more by commercial search engines to address information needs directly on the results page, understanding the properties of such objects and their influence on searchers is an essential aspect of modern web search science. The work presented throughout this thesis attempts the task of studying composite objects by exploring users’ perspectives on accessing and aggregating diverse content manually, by analysing the effect composite objects have on search behaviour and perceived workload, and by investigating different approaches to constructing such objects from diverse results. Overall, our experimental findings suggest that items which play a central role within composite objects are decisive in determining their usefulness, and that the overall properties of composite objects (i.e., relevance, diversity and coherence) play a combined role in mediating object usefulness