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Assessing changes in coverage, recall, review, conclusions and references not found when searching fewer databases. In randomly selected 60 Cochrane reviews, we checked included study publications' coverage (indexation) and recall (findability) using different search approaches with MEDLINE, Embase, and CENTRAL and related them to authors' conclusions and certainty. We assessed characteristics of unfound references. Overall 1989/2080 included references, were indexed in ≥1 database (coverage = 96%). In reviews where using one of our search approaches would not change conclusions and certainty (n = 44-54), median coverage and recall were highest (range 87.9%-100.0% and 78.2%-93.3%, respectively). Here, searching ≥2 databases reached >95% coverage and ≥87.9% recall. In reviews with unchanged conclusions but less certainty (n = 2-8): 63.3%-79.3% coverage and 45.0%-75.0% recall. In reviews with opposite conclusions (n = 1-3): 63.3%-96.6% and 52.1%-78.7%. In reviews where a conclusion was no longer possible (n = 3-7): 60.6%-86.0% and 20.0%-53.8%. The 265 references that were indexed but unfound were more often abstractless (30% vs. 11%) and older (28% vs. 17% published before 1991) than found references. Searching ≥2 databases improves coverage and recall and decreases the risk of missing eligible studies. If researchers suspect that relevant articles are difficult to find, supplementary search methods should be used.

Retrieving the qualitative literature can be challenging, but the number and specific choice of databases are key factors. The aim of the present study is to provide guidance for the choice of databases for retrieving qualitative health research. Seventy-one qualitative systematic reviews, from the Cochrane Database of Systematic Reviews and JBI database of Systematic Reviews and Implementation Reports, including 927 qualitative studies, were used to analyze the coverage of the qualitative literature in nine bibliographic databases. The results show that 94.4% of the qualitative studies are indexed in at least one database, with a lower coverage for publication types other than journal articles. Maximum recall with two databases is 89.1%, with three databases recall increases to 92% and maximum recall with four databases is 93.1%. The remaining 6.9% of the publications consists of 1.3% scattered across five databases and 5.6% that are not indexed in any of the nine databases used in this study. Retrieval in one or a few—although well selected—databases does not provide all the relevant qualitative studies. The remaining studies needs to be located using several other databases and alternative search strategies. •94.4% of the included studies in qualitative reviews are indexed in at least one of the nine databases. Coverage is higher for journal articles.•Using four databases, it is possible to retrieve 93.1% of the publications.•Retrieval in one or a few databases does not provide all the relevant qualitative literature, and the remaining studies need to be located using several other databases and alternative search strategies.

In health sciences, comprehensive literature searches are crucial for ensuring the accuracy and completeness of systematic reviews. Relying on only a few databases can lead to the omission of relevant studies. The variability in database coverage for different specialties means that important literature might be missed if searches are not broadened. Supplementary databases can enhance the thoroughness of literature reviews, but the efficiency and necessity of these additional searches remain subject to debate. This study aims to explore methods for retrieving publications not indexed in PubMed and Embase, examining coverage of various specialties to determine the most effective search strategies for systematic reviews. We selected reviews from the following Cochrane review groups: public health, incontinence, hepato-biliary, and stroke groups. All reviews published in these groups between 2017 and 2022 were analyzed. Publications included in these reviews were manually searched for in PubMed and Embase. If the publication was not found, additional databases such as Cochrane Library, PsycInfo, CINAHL, and ClinicalTrials.gov were searched. Descriptive statistics were used to analyze the data. The mean coverage of publications in PubMed and Embase across all four speciality groups was 71.5%, with individual group coverage ranging from 64.5% to 75.9%. An average of 5.8% of publications could not be retrieved in any of the databases studied. Additional databases varied in their coverage. While PubMed and Embase provide substantial coverage, supplementary databases can increase retrieval of more relevant studies and are essential for a comprehensive literature search. •Databases beyond PubMed and Embase should be included in comprehensive literature searches.•Database coverage varies significantly among review groups.•Supplementary databases enhance the thoroughness of literature searches.•Diverse methodologies, including grey literature and trial protocols, are needed.

The objective of this study was to analyze the degree of changes in indexed journals within a database using SCImago Journal Rank (SJR) as a proxy for Scopus. We downloaded SJR-listed journal data to examine journal evolution over the past decade (2013–2022) and analyzed them in terms of the following metrics: the number of journals, growth rates, normalized growth and the Jaccard index. The findings revealed a significant increase in Scopus-indexed journals during this period, with journals growing from 23,957 in 2013 to 27,033 (12.8 percent) but declining after peaking at 28,099 in 2019. Open access (OA) journals exhibited remarkable growth and higher turnover (48.3 percent) than non-OA journals (2.3 percent). For a thorough assessment of journal growth and overlap, we propose using a quadrant analysis. Using this approach, we found an inverse relationship between the normalized growth rate and the Jaccard index across different subject areas and countries. The methods described in this study can be used to analyze changes in indexed journals in other databases and thus contribute to a better understanding of its indexed journals.

Medline/PubMed is often first choice for health science researchers when doing literature searches. However, Medline/PubMed does not cover the health science research literature equally well across specialties. Embase is often considered an important supplement to Medline/PubMed in health sciences. The present study analyzes the coverage of Embase as a supplement to PubMed, and the aim of the study is to investigate if searching Embase can compensate for low PubMed retrieval. The population in this study is all the included studies in all Cochrane reviews from 2012 to 2016 across the 53 Cochrane groups. The analyses were performed using two units of analysis (study and publication). We are examining the coverage in Embase of publications and studies not covered by PubMed (25,119 publications and 9,420 studies). The results showed that using Embase as a supplement to PubMed resulted in a coverage of 66,994 publications out of 86,167 and a coverage rate of 77.7, 95% CI [75.05, 80.45] of all the included publications. Embase combined with PubMed covered 48,326 out of 54,901 studies and thus had a coverage rate of 88.0%, 95% CI [86.2, 89.9] of studies. The results also showed that supplementing PubMed with Embase increased coverage of included publications by 6.8 percentage points, and the coverage of studies increased by 5.5 percentage points. Substantial differences were found across and within review groups over time. The included publications and studies in some groups are covered considerably better by supplementing with Embase, whereas in other groups, the difference in coverage is negligible. However, due to the variation over time, one should be careful predicting the benefit from supplementing PubMed with Embase to retrieve relevant publications to include in a review.

本研究旨在比較商業與開放取用兩種學術傳播工具，透過實際操作商業引文資料庫Web of Science與Scopus與搜尋引擎Microsoft Academic，匯集式機構典藏系統OpenDOAR和物理學專科特性的Astrophysics Data System開放取用引文系統，分析其收錄書目資料的正確性與重複性。本研究以諾貝爾物理學2001年至2013年得獎者之著作為研究樣本，進行書目資料剖析，包括排序、比對、刪除、聚集與統計，並相互交叉比對分析結果，比較各商業資料庫與開放取用系統之優劣，並根據分析結果提出建議。本研究結果期望能提供圖書館選擇引文索引資料庫與建置機構典藏系統，或引文資料庫與系統未來發展之參考。此外，亦可作為研究人員進行學術傳播與學術單位進行學術評鑑採用之指標與工具之建議。

This chapter presents a list of terms regarding statistical measures for scientific productivity, commencing with the alphabet D. It includes the meaning of database citation potential, database coverage, discounted cumulated impact (DCI) index, and diffusion score. Databases are published electronically by database producers which can be public institutions or private firms, and data can be accessed freely or by license agreement from vendors. DCI index is an index proposed at the researcher level to smooth the role of old citations but rewarding the author for receiving new citations even if the publication is old. Diffusion score is an indicator to measure the diffusion of scientific research, aimed to catch not only variety but also diversity among citing articles in different research fields. The higher the values of the diffusion score, the greater the infiltration into external fields.

Systematic literature reviews in educational research have become a popular research method. A key point hereby is the choice of bibliographic databases to reach a maximum probability of finding all potentially relevant literature that deals with the research question analyzed in a systematic literature review. Guidelines and handbooks on review recommend proper databases and information sources for education, along with specific search strategies. However, in many disciplines, among them educational research, there is a lack of evidence on the relevance of databases that need to be considered to find relevant literature and lessen the risk of missing relevant publications. Educational research is an interdisciplinary field and has no core database. Instead, the field is covered by multiple disciplinary and multidisciplinary information sources that have either a national or international focus. In this article, we discuss the relevance of seven databases in systematic literature reviews in education, based on results of an empirical data analysis of three recently published reviews. To evaluate the relevance of a database, the relevant literature of those reviews served as the gold standard. Results indicate that discipline-specific databases outperform international multidisciplinary sources, and a combination of discipline-specific international and national sources is most efficient in finding a high proportion of relevant literature. The article discusses the relevance of the databases in relation to their coverage of relevant literature, while considering practical implications for researchers performing a systematic literature search. We, thus, present evidence for proper database choices for educational and discipline-related systematic literature reviews.

The expansion of Web of Science Core Collection (WoSCC) over the recent years has partially accounted for the “norm” of growth of research output in many bibliometric analysis studies. However, the expansion patterns of different citation indexes may be different, which may benefit some disciplines but hinder others. Utilizing Science Citation Index Expanded (SCIE), Social Sciences Citation Index (SSCI), and Arts & Humanities Citation Index (A&HCI), this study attempts to elaborate on WoSCC’s coverage expansion patterns among these three databases from 2001 to 2020. Results show that different from SCIE/SSCI, both the annual publication volumes in the A&HCI database and all A&HCI journals have remained relatively stagnant in all document types considered scenario or have gained relatively slight increases in only citable items considered scenario. Although the number of A&HCI journals also has increased remarkably, the average journal publication volume of A&HCI journals has decreased gradually if all document types are considered or kept relatively stagnant when citable items only are considered. Besides, the A&HCI database has ceased the systematic index of individually selected items from SCIE/SSCI journals since 2018. The study finally discusses the possible causes and consequences of the unbalanced expansion of WoSCC’s different citation indexes.

Large databases have played a critical role in pharmacoepidemiological research in the last decade, with this role likely to gain further importance in the future. The aim of the present paper is to describe the characteristics, the recent use, and the limitations of the German longitudinal prescription (LRx) database. The LRx database contains patient-level data on prescriptions collected in retail pharmacies, corresponding to ~ 80% of prescriptions reimbursed by statutory health insurance funds in Germany. The LRx database includes a higher proportion of older adults and women compared to the overall German population with statutory health insurance. Coverage per family of drugs ranges from 71.8% for antiepileptics to 94.7% for urological agents. Multiple pharmacoepidemiological studies based on the data from the German LRx database have been published in the last years on topics such as patterns of prescription and treatment adherence and persistence. A large number of disorders have been investigated in this research (e.g., type 2 diabetes, inflammatory diseases, and psychiatric conditions). The major limitations of the LRx database are the lack of formal diagnoses and the absence of hospital data. In conclusion, the German LRx database could be a key source of data for future pharmacoepidemiological studies.