Author-level metrics measure the impact of the scholarly output of a single researcher. Author-level metrics are designed to help researchers assess the cumulative impact of their work, rather than the impact of a single publication. All author-level metrics are derived from article-level metrics: they aggregate or summarise the impact of an author's publications.
Notes and Limitations
As a "general rule of thumb:
"However, the reverse is not necessarily true. If an academic shows weak citation metrics, this may be caused by a lack of impact on the field, but also by one or more of the following:
Source: Anne-Wil Harzing, Publish or Perish
The h-index is intended to reflect ongoing impact. A h-index of x for an author signifies that the author has published x papers each of which has been cited at least x times. It is a commonly used indicator of research output which reflects both the number of publications and the distribution of citations to those publications.
A h-index of 5 for an author signifies that the author has published 5 papers each of which has been cited at least 5 times. A h index can be created for a single author or a research unit. It is important to remember that the index is only useful in comparing scientists at the same career stage and working within the same field as citation conventions differ substantially between disciplines.
It is important to note that whilst the methodology used to create the metrics across systems will be the same the underlying dataset differences will result in variances.