The Obsolescence of Cited and Citing Journals: Half-Lives and Their Connection to Other Bibliometric Indicators

This study analyzes the half-lives of all journals from the 1997–2018 period that were included in the Journal Citation Reports (JCR): Science (JCR-SE) and Social Sciences (JCR-SSE) JCR Editions, and in some narrower branches of science specially distinguished on the basis of WoS subject categories. The findings show that the values of the Cited Half-Life (CdHL) and Citing Half-Life (CgHL) indicators are almost always positive over the entire 22-year study period and for the entire global body of journals in the JCR, individual JCR editions, and each of the specially compiled sets of All Journals and Core Journals. They confirm the long-established fact that the CdHL and CgHL depend on the branch of science and characterize that branch and demonstrate that half-life values for social sciences and humanities are generally higher than for hard sciences. A correlation between half-life values and journal impact factors and numbers of Citable Items (articles, reviews, and conference proceedings that can be cited) is clearly shown. These features of half-lives are important to consider when goal setting and forecasting the development of scientific research.