Empirical relationship between the number of review and research articles

Abstract

In this contribution, an empirical relationship between the number of review and research articles published per year was searched. The simple idea based on proportionality (lin‑ earity) between the numbers of both kinds of articles was expressed in terms of a quad‑ ratic relationship, in which the quadratic member can refect negative or positive deviations from the assumed linearity. The quadratic relationship was able to describe beginning peri‑ ods of research felds as well as their mature phases and to detect the unpredictably high number of review articles. It was verifed by the articles published in 20 various research felds taken from the Web of Science during diferent time spans.