## 3 Results for the Research Questions
### RQ2: What Are the Expertise Sources Used for Experts Finding Systems?
#### 3.3.1 RQ3a: What Are the Differences between Expertise Retrieval and Expertise Seeking? In this question, the authors differentiate between the expertise retrieval and the expertise seeking tasks using three dimensions--definition, research area, and sociotechnical perspective. As for the definition of expertise retrieval, the authors in reference [68] stated that the expertise retrieval involves the identification of a set of people who possessed the necessary expertise for a specific query. Generally, the expertise of any candidate is based on all documents related to this candidate. This document-based model was seen to be a state-of-the-art approach that estimated the weighted sum of the retrieval scores for all the documents associated with an expert candidate as the measure of the candidate's expertise. After the introduction of the expert finding tasks in the Text Retrieval Conference (TREC) in 2005, there has been an increased interest in the application of the expertise retrieval task in research. While the definition of expertise seeking can be stated as the activity that involves the selection of people as a consultation source based on the information needs. People can be used as sources if they have a higher knowledge than what they usually record in documents. This need for further human-based knowledge can develop in the course of a conversation. These human experts can offer their expertise on various issues [81; 82]. Expertise seeking helps in developing experts can offer their expertise on various issues [90; 91]. Expertise seeking helps in developing models that determine the manner in which the relevant experts are selected. The relevant models help in identifying the factors that can play a vital role in the expert selection [92]. From research area dimension, some researchers [1; 43] considered the expertise retrieval system as a subject of further research in the area of information retrieval. Expertise seeking is considered to be \begin{table}
\begin{tabular}{c c c} \hline \hline
**Channel** & **Expertise Sources** & **Studies** \\ \hline \multirow{8}{*}{**Category**} & Publications & [36; 38; 44; 48; 49; 53; 58; 59; 61; 62; 66; 67; 68; 70; 71; 73; 80] \\  & Movies & [42] \\  & Medicine related documents, & [80; 81] \\  & Employee documents & [15; 77] \\  & Bug repository & [36] \\  & Transactional data & [79] \\  & Enterprise terminologies’ & [78] \\  & Relevance feedback & [74] \\  & Log repository & [35] \\  & Homepages & [5; 26; 27; 44; 46] \\  & Emails & [87] \\  & Social network & [20; 21; 37; 56; 76; 86] \\  & Forums & [84; 85] \\  & Posts and questions tags & [16; 17; 19; 44; 82; 83] \\  & Employee documents, publications and & [75] \\  & projects & [22] \\  & Proposals, publications & [39] \\  & homepages and social network & [41] \\  & Publications, supervised student theses, & [43; 44] \\  & course descriptions, and research descriptions & [44; 47; 55; 69; 88] \\  & Publications and social networks & [44; 47; 55; 69; 88] \\  & Publications and homepages & [40] \\  & publications and citation data & [48] \\  & Projects–homepages & [65] \\  & publications, citations, homepages, & [60] \\  & Experience & \\  & webpages, project/grant repositories, citation & [44] \\  & indexes & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Expertise sources. included in the knowledge management research area, which effectively uses human knowledge in an organisation. Finally, from a sociotechnical perspective, expertise retrieval systems mainly focus on the development of content-based algorithms, similar to a document search. Such algorithms identified all experts by analysing the content of all the related documents. A majority of the research in the expertise retrieval system was dependent on a system-centered perspective, which concentrated on the identification of good matches between the need for expertise and the content of the documents related with the experts.