Chapter 8 Search Engines and Rank Correlation

Purpose — Ranking is a natural task for a search engine; a search engine result page is the most common example. This chapter aims at illustrating the motivations and the concepts of rank correlation in a practical way for the researchers active in the different domains of search engines. Methodology/approach — To this end, this chapter provides a survey according to a topic-oriented basis of the search engine evaluation literature specifically devoted to or based on rank correlation; the chapter explains and illustrates how statistics is the only approach to rank correlation. Findings/research limitations/implications — The chapter introduces the pros and cons of rank correlation measures through a light-weight formal description and a number of concrete examples to find the measure that better fit a context. Practical implications — This chapter provides a blueprint for the application of rank correlation within scientific experimentation or item/service recommendation. Social implications — Rank correlation analyses impact on the success or failure of a search engine in performing the tasks for which it has been designed and hence on the people's daily life activities. Originality/value of paper — This chapter places rank correlation within a scientific research perspective and in particular connects to and complements documentation on search engine evaluation.