Abstract: New sources of citation data have recently become available, such as Microsoft Academic, Dimensions, and the OpenCitations Index of CrossRef open DOI-to-DOI citations (COCI). Although these have been compared to the Web of Science Core Collection (WoS), Scopus, or Google Scholar, there is no systematic evidence of their differences across subject categories. In response, this paper investigates 3,073,351 citations found by these six data sources to 2,515 English-language highly-cited documents published in 2006 from 252 subject categories, expanding and updating the largest previous study. Google Scholar found 88% of all citations, many of which were not found by the other sources, and nearly all citations found by the remaining sources (89–94%). A similar pattern held within most subject categories. Microsoft Academic is the second largest overall (60% of all citations), including 82% of Scopus citations and 86% of WoS citations. In most categories, Microsoft Academic found more citations than Scopus and WoS (182 and 223 subject categories, respectively), but had coverage gaps in some areas, such as Physics and some Humanities categories. After Scopus, Dimensions is fourth largest (54% of all citations), including 84% of Scopus citations and 88% of WoS citations. It found more citations than Scopus in 36 categories, more than WoS in 185, and displays some coverage gaps, especially in the Humanities. Following WoS, COCI is the smallest, with 28% of all citations. Google Scholar is still the most comprehensive source. In many subject categories Microsoft Academic and Dimensions are good alternatives to Scopus and WoS in terms of coverage.
“In this blog post, I will talk specifically on a very important source of data used by Academic Search engines – Microsoft Academic Graph (MAG) and do a brief review of four academic search engines – Microsoft Academic, Lens.org, Semantic Scholar and Scinapse ,which uses MAG among other sources….
We live in a time, where large (>50 million) Scholarly discovery indexes are no longer as hard to create as in the past, thanks to the availability of freely available Scholarly article index data like Crossref and MAG.”
Abstract: Rigorous evidence identification is essential for systematic reviews and meta?analyses (evidence syntheses), because the sample selection of relevant studies determines a review’s outcome, validity, and explanatory power. Yet, the search systems allowing access to this evidence provide varying levels of precision, recall, and reproducibility and also demand different levels of effort. To date, it remains unclear which search systems are most appropriate for evidence synthesis and why. Advice on which search engines and bibliographic databases to choose for systematic searches is limited and lacking systematic, empirical performance assessments.
This study investigates and compares the systematic search qualities of 28 widely used academic search systems, including Google Scholar, PubMed and Web of Science. A novel, query?based method tests how well users are able to interact and retrieve records with each system. The study is the first to show the extent to which search systems can effectively and efficiently perform (Boolean) searches with regards to precision, recall and reproducibility. We found substantial differences in the performance of search systems, meaning that their usability in systematic searches varies. Indeed, only half of the search systems analysed and only a few Open Access databases can be recommended for evidence syntheses without adding substantial caveats. Particularly, our findings demonstrate why Google Scholar is inappropriate as principal search system.
We call for database owners to recognise the requirements of evidence synthesis, and for academic journals to re?assess quality requirements for systematic reviews. Our findings aim to support researchers in conducting better searches for better evidence synthesis.
Abstract: In the last 3 years, several new (free) sources for academic publication and citation data have joined the now well-established Google Scholar, complementing the two traditional commercial data sources: Scopus and the Web of Science. The most important of these new data sources are Microsoft Academic (2016), Crossref (2017) and Dimensions (2018). Whereas Microsoft Academic has received some attention from the bibliometric commu-nity, there are as yet very few studies that have investigated the coverage of Crossref or Dimensions. To address this gap, this brief letter assesses Crossref and Dimensions cover-age in comparison to Google Scholar, Microsoft Academic, Scopus and the Web of Science through a detailed investigation of the full publication and citation record of a single academic, as well as six top journals in Business & Economics. Overall, this first small-scale study suggests that, when compared to Scopus and the Web of Science, Crossref and Dimensions have a similar or better coverage for both publications and citations, but a substantively lower coverage than Google Scholar and Microsoft Academic. If our find-ings can be confirmed by larger-scale studies, Crossref and Dimensions might serve as good alternatives to Scopus and the Web of Science for both literature reviews and citation analysis. However, Google Scholar and Microsoft Academic maintain their position as the most comprehensive free sources for publication and citation data
Abstract: Closed and proprietary infrastructures limit the accessibility of research, often putting paywalls in front of scientific knowledge. But they also severely limit reuse, preventing other tools from building on top of their software, data, and content. Using the example of Google Scholar, I will show how these characteristics of closed infrastructures impede innovation in the research workflow and create lock-in effects. I will also demonstrate how open infrastructures can help us move beyond this issue and create an ecosystem that is community-driven and community-owned. In this ecosystem, innovation thrives, as entry barriers are removed and systems can make use of each other’s components. Specific consideration will be given to open source services and non-profit frontends, as they are often overlooked by funders, but represent the way researchers engage with open science.
“You know you have access and you have access now. However, the discovery process for open access articles isn’t necessarily the same as subscription searching. Especially if you do not have access to specific subscription databases.
This guide is meant to help individuals, of any background, search more easily for open access articles….”
As a starting point for search, A&Is seem to be in a slight decline when looked at in aggregate across all regions and sectors, but remain the most important. Figure 4, p11 ? Academic researchers in high income countries now rate library discovery as highly as A&Is, and rate academic search engines as the most important discovery resource when searching for journal articles. Figure 11, p18 ? Library discovery services have made significant advances in importance in search for academic researchers, and for all roles in hard sciences in the academic sector. As an average across all subjects and sectors, however, they have not grown in importance in since 2012. Figure 4, p11; Figure 7, p14; Figure 11, p18 ? More than half of all journal content delivery appears to be from free incarnations of articles. There appears to be a clear PubMedCentral effect in the medical sector. Social media sites appear to be a significant source of free articles in lower income countries. Figure 37, p39 ? In academic STM in higher income countries, academic search engines are now more important than general search engines. Figure 4, p11 ? Table of Contents alerts have reduced in popularity in all measures across the survey. Figure 26, p31; Figure 35, p37 ? There appears to be an increased role for social media in discovery. Figure 9, p16 ? Online book discovery varies significantly by sector, with academics preferring library web pages marginally over general web search engines, the medical sector preferring A&I services and library web over search engines, but all other sectors preferring search engines over other forms of discovery. Figure 31, p34 ? Publisher web sites are becoming more popular as a search resource, although this is less true for people in wealthier countries. Figure 10, p17; Figure 18, p24 ? Google Scholar is used more than Google in the academic sector, but less than Google in all other sectors. Figure 22, p27 ? A perceived lack of awareness of Google Scholar in poorer nations appears to be leading to a reduced use of free incarnations of content in institutional repositories from these regions. Page 40 ? Readers in low income countries use their mobiles to access journals more than their counterparts in richer countries. However, access by phone still accounts for only about 10% of the use. Figure 42, p44 ? A&Is continue to be the most important search method in the medical sector. Figure 15, p21 ? The primary method of journals discovery is search, but even more so for online books. Figure 33, p35 ? App use for journal discovery is still low. Figure 45, p45 ? The most highly sought-after features of journal web sites are changing. Figure 49, p48 …”