network analysis
本研究以發表場域-作者-耦合(Venue-Author-Coupling，VAC)、期刊共被引分析(journal co-citation analysis)、主題分析(topic analysis)和連結編輯委員會成員(interlocking editorial board membership)等四個面向分析資訊科學與圖書館學的期刊網絡。這個研究分析的期刊範圍為2008年 JCR (Journal Citation Report)資訊科學與圖書館學分類的58種期刊，在2005到2009年間的出版資料。分析資料的相關數據如Table 1:
本研究利用VAC代表期刊的生產者(producers)的相似性，根據每一對期刊間相同的作者數量測量它們的接近程度，其原理建立在作者會選擇主題或社會性相似(thematically or socially similar)的期刊發表。期刊共被引分析(McCain, 1991)計算每一對期刊被共同引用的次數，本研究用來測量作品(artifacts)間的相似程度。本研究以修改自LDA模型(Blei et al. 2003)的ACT(Author-Conference-Topic)模型(Tang et al., 2008)透過關鍵詞(keywords)在主題上的分布以及主題在作者及發表場域(期刊)上的分布，本研究以餘弦(cosine)測量評估期刊之間的相似程度。連結編輯委員會成員則是編輯委員會上的共同成員數測量期刊間的相似程度。兩種期刊間共同的成員愈多，代表這兩種期刊在認知上或是社會性上愈相似。
根據上面的四種期刊間的相似程度所得到的結果，除了進行階層式集群分析(hierarchical cluster analysis)之外，也用來建立網絡，以Kamada-Kawaii 法呈現網絡的型態。分析得到的四種網絡並且以二次指派程序(Quadratic Assignment Procedure) (Lawler 1963)比較網絡之間可能的相關性(correlation)。
VAC方法得到的期刊網絡如下
四個集群分別為MIS(黃)、IS(藍)、LS(綠)以及專門性期刊(紅)。其中的MIS期刊集群與其他的集群相當分離。IS與LS距離較近。相較於其他三個期刊集群，專門性期刊彼此間的連結較弱。
期刊共被引分析所得的網絡如下：
主題模型產生的五個主題如Table 2
五個主題在網絡上的分布如下圖
MIS(黃)仍然與其他集群較為分離，但與健康和傳播(communication)等專門性期刊的距離較近。IS(藍)和LS(粉紅)的位置與VAC和期刊共被引分析的網絡上有所不同。圖書館服務與實務(綠)與專門性期刊和LS很接近。
在利用連結編輯委員會成員的期刊網絡上，有10種期刊沒有和其它期刊有共同編輯委員。其餘的集群分為四群。以傳播研究相關的期刊是新增加的集群(綠)。
四個網絡的QAP結果如Table 3
總結以上，在JCR的資訊科學與圖書館學分類下約略可以將期刊分為四個集群：MIS、IS、LS和傳播相關的期刊。MIS相較來說較為獨立。另外，QAP的結果可以看到編輯委員會成員的結果與期刊共被引分析有很高的相關性，其原因可能是由於擔任編輯委員的研究人員往往有較好的學術成就，被引用的機會較高。編輯委員會成員與VAC有較高的相關性，其原因也可能是編輯委員有較高的生產力。運用多種面向的分析可以較全面地了解整個學術傳播網絡。
Fifty-eight journals from the Information Science and Library Science category in the 2008 Journal Citation Report were studied and the network proximity of these journals based on Venue-Author-Coupling (producer), journal co-citation analysis (artifact), topic analysis (concept) and interlocking editorial board membership (gatekeeper) was measured. The resulting networks were examined for potential correlation using the Quadratic Assignment Procedure.
The VAC approach is used to represent the producers in this dataset. This approach measures journal proximity based on the number of authors shared by each journal pair. The VAC approach is based on the idea that an author’s choice of publication venue reflects similarity judgments authors are likely to choose venues that are thematically or socially similar.
Artifacts are measured by means of journal co-citation. This measure, introduced by McCain (1991), refers to the appearance of two journals in the same reference list of an article. The more frequently two journals appear in the same reference lists, the greater the similarity between the two journals. The journal co-citation approach measures journal proximity by the frequency with which each journal pair is co-cited by the same articles.
Topic modeling is used to capture concepts. ... The technique adopted here, the author-conference-topic (ACT) model (Tang et al., 2008), extends the LDA model by considering the author and publishing venue of the articles. LDA was developed originally as a topic modeling technique concerning the probability distribution of keywords for topics, and is particularly helpful with the ‘‘classification, novelty detection, summarization, and similarity and relevance judgment’’ of large-scale data (Blei et al. 2003, p. 993). ... This model extends the idea of LDA by taking into account the authors and publishing venues, and estimates not only the distribution of words on topics, but also the distribution of authors and venues on the topics modeled. ... Here, the outcome of the ACT model is the probability distribution of each author and each journal over topics, and the journal proximity is calculated using the cosine similarity of the journals.
The interlocking editorship approach, employed by Ni and Ding (2010), measures journal proximity based on common editorial board membership. The number of editorial board members that two journals share can be viewed as an indicator of journal similarity. ... Thus, it can be expected that if two journals have scholars in common on their editorial boards, these two journals have some degree of similarity, either cognitively or socially.
The journals were clustered using a hierarchical clustering technique with squared Euclidean distance and Ward’s method. Each journal clustering was displayed as a network (Kamada-Kawaii layout); each node (journal) was colored according to the hierarchical clustering result with the size of a
node proportional to its centrality (either degree or closeness).
Additionally, a comparison of journal proximity results was conducted using the Quadratic Assignment Procedure (QAP). QAP is commonly used in social network analysis as a means of investigating correlations between two networks. ... (Lawler 1963).
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