Impact and centrality of scientific disciplines

The Scimago Journal Rank (SJR) is a metric that captures the centrality of a journal across an all-discipline article network, while the impact factor (IF) is the average incoming citations of a journal. We analyzed SJRs and IFs of the journals belonging to the SJR first quartile from 2013 to 2020 in 7 disciplines: mathematics, biology, physics, medicine, social sciences, chemistry, and engineering. We show that biology is the most central discipline, followed by physics and chemistry. These three disciplines also present the highest IFs. Mathematics journals display a low IF (the second-lowest among disciplines), but possesses an intermediate centrality. While the average IF has increased over the last years, the SJR average has decreased. Gini coefficients show that SJR is a slightly more egalitarian metric than IF. We discuss some possible origins of these findings.