Reality or Illusion: Comparing Google Scholar and Scopus Data for Predatory Journals.

This research compares the performance measures reported by two bibliographic databases relevant to a set of authors who have published in predatory journals. The reliability of decision-making based on the information provided by uncontrolled bibliographic databases is examined to support rational decisions. A sample of authors who published in predatory journals was selected in order to compare each author's research performance as reported by Google Scholar (GS) and Scopus. The number of articles, citations, and h-indices were used for the comparison. Correlation analysis, polynomial regression, k-means clustering, significant tests, and simple descriptive statistics were employed to examine the data. The number of articles, citations, and h-indices correlated strongly between the two databases. However, these three measures were all significantly higher in GS than they were in Scopus. The articles published in predatory journals received less attention as compared to that received by the articles published in genuine journals. Two polynomial models of two degrees were implemented to interpolate the number of citations based on the number of articles in GS and Scopus separately. The number of articles and citations were more reliable measures in Scopus than in GS. However, the h-index was more reliable in GS. Overall, Scopus displayed higher stability than did GS. The combined behavior of the three performance measures showed some resemblance in the two databases. A study that especially focuses on the research performance of authors who published in predatory journals has not yet been compared for the different implications given for their data in uncontrolled and controlled bibliographic databases. Therefore, the findings of the current research let us evaluate such authors rationally. [ABSTRACT FROM AUTHOR]