Citation-Based Journal Rankings: Key Questions, Metrics, and Data Sources

This guide presents nine key questions that can help researchers make good use of citation-based journal rankings (metrics) in the natural and social sciences. The nine questions address the characteristics that distinguish one metric from another: the source documents, the citation-counting window, the document types counted, the cited-document window, the impact of highly cited documents, the treatment of self-citations, the distinction between size-dependent and size-independent metrics, the use of normalization to account for disciplinary differences in impact, and the use of weighting to account for the impact or centrality of each citing journal. Next, the guide reviews 19 standard citation metrics, including the h index, g index, impact factor, source normalized impact per paper, eigenfactor, article influence score, and SCImago journal rank. Three underlying data sources (Web of Science, Scopus, and Google Scholar) are described, along with six major data download sites: Journal Citation Reports, Eigenfactor, CWTS Journal Indicators, SCImago, Scopus Journal Metrics, Cabell's International, and Google Scholar Metrics. The paper summarizes the main criticisms of citation metrics and concludes with suggestions for their further development, dissemination, and use.