How many results per page? a study of SERP size, search behavior and user experience

The provision of "ten blue links" has emerged as the standard for the design of search engine result pages (SERPs). While numerous aspects of SERPs have been examined, little attention has been paid to the number of results displayed per page. This paper investigates the relationships among the number of results shown on a SERP, search behavior and user experience. We performed a laboratory experiment with 36 subjects, who were randomly assigned to use one of three search interfaces that varied according to the number of results per SERP (three, six or ten). We found subjects' click distributions differed significantly depending on SERP size. We also found those who interacted with three results per page viewed significantly more SERPs per query; interestingly, the number of SERPs they viewed per query corresponded to about 10 search results. Subjects who interacted with ten results per page viewed and saved significantly more documents. They also reported the greatest difficulty finding relevant documents, rated their skills the lowest and reported greater workload, even though these differences were not significant. This work shows that behavior changes with SERP size, such that more time is spent focused on earlier results when SERP size decreases.