Felipe Moraes Gomes defends PhD thesis on Collaborative Search

Examining the Effectiveness of Collaborative Search Engines

by Felipe Moraes Gomes

Although searching is often seen as a solitary activity, searching in collaboration with others is deemed useful or necessary in many complex situations such as: travel planning; online shopping; looking for health related information; planning birthday parties; working on a group project; or finding a house to buy. Researchers have found that complex search tasks can be executed more effectively and efficiently, achieve higher material coverage, and enable higher knowledge gains in an explicit collaborative setting than if conducted in isolation. However, even though researchers have carefully designed several Collaborative Search (CSE) user studies, there is still conflicting evidence or a lack of evidence on the effectiveness of CSE systems. Thus, in this thesis, we focus on examining the effectiveness of CSE systems in two parts.

In the first part, we shed light on the effectiveness of CSE to support two group configurations, namely group sizes and users’ roles. Past collaborative search studies have had a strong focus on groups of two or three collaborators, thus naturally limiting the number of experimental conditions that could increase quickly. Therefore, there is a lack of evidence suggesting the extent to which
a CSE system can support group sizes beyond these commonly investigated group sizes. Thus, in Chapter 3, we study CSE system effectiveness with group size as the primary dependent variable. Here, we vary group sizes from two to six collaborators, with six as our upper bound due to limitations on our available resources.

In Chapter 4, we focus on roles in CSE. Roles can determine how a group splits up the search task, and determines each group member’s function (e.g., one group member is responsible for finding documents and reading and evaluating them, with a further member responsible for in-depth reading and evaluating of the aforementioned documents). In particular, when the CSE system assigns a role to each group member, researchers have hypothesised that a group may reduce the time spent communicating and coordinating the task, and make the search process more efficient and successful than groups without
role assignment. However, past user studies have provided contradicting evidence as to the utility of assigned roles in CSE. Thus, in Chapter 4, we provide more evidence to settle the question of the effectiveness of CSE systems when used by groups with pre-assigned roles versus groups without pre-assigned roles.

In the second part of this thesis, we make our group configurations constant, particularly, group sizes are set to up to three people, and group members receive the same role. We then turn to a different perspective and focus on examining the effectiveness in two contexts: Search as Learning (SAL) and collaborative online shopping. Search activities for human learning involve multiple iterations that require cognitive processing and interpretation, often requiring the searcher to spend time scanning/viewing, comparing, and evaluating information. However, web search engines are not built to support users in the search tasks often required in learning situations. When people use search as a learning activity, it can be an individual activity or a collaborative activity (e.g., group projects). Hence, in Chapter 5, we tackle the challenge of identifying the impact of web search engines on the (single-search or collaborative search) users’ ability to learn compared to learning acquired via high-quality learning materials as a baseline.

In Chapter 6, we look at a further context: collaborative online shopping. In collaborative online shopping, a group of people come together to make a decision to purchase a product that meets the various group members’ requirements and opinions. While shopping together, search is an important part of the task in order to search for products in a catalogue that is available in an e-commerce website. One important aspect of collaborative shopping is supporting awareness and sharing of knowledge as it can enable a sense of co-presence, which helps groups make a decision that satisfies each group member’s requirements and wishes. As search is a significant part of a collaborative online shopping experience, CSE systems are suitable for executing such tasks. However, there is insufficient evidence of how well can CSE systems support a group of users to search for online products together and make a group decision. Hence, in Chapter 6, we explore the effects of increased awareness and sharing of knowledge (co-presence) using a CSE system in collaborative shopping on the group decision making process.

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