  The academic publishing world is changing significantly, with ever-growing
numbers of publications each year and shifting publishing patterns. However,
the metrics used to measure academic success, such as the number of
publications, citation number, and impact factor, have not changed for decades.
Moreover, recent studies indicate that these metrics have become targets and
follow Goodhart's Law, according to which "when a measure becomes a target, it
ceases to be a good measure." In this study, we analyzed over 120 million
papers to examine how the academic publishing world has evolved over the last
century. Our study shows that the validity of citation-based measures is being
compromised and their usefulness is lessening. In particular, the number of
publications has ceased to be a good metric as a result of longer author lists,
shorter papers, and surging publication numbers. Citation-based metrics, such
citation number and h-index, are likewise affected by the flood of papers,
self-citations, and lengthy reference lists. Measures such as a journal's
impact factor have also ceased to be good metrics due to the soaring numbers of
papers that are published in top journals, particularly from the same pool of
authors. Moreover, by analyzing properties of over 2600 research fields, we
observed that citation-based metrics are not beneficial for comparing
researchers in different fields, or even in the same department. Academic
publishing has changed considerably; now we need to reconsider how we measure
success.
