"Research impact is the demonstrable contribution that excellent research makes to society and the economy. It embraces all the diverse ways that research-related skills benefit individuals, organisations and nations." - Research Councils UK (RCUK)
Why is it important?
It is important that researchers know their impact as it can help: support applications for tenure or promotion; justify requests for grants and other funding; quantify, and determine how their research is being used; identify other researchers or institutions that are using their work; and identify other researchers, and potential collaborators, in their field.
Journal Metrics, such as Impact Factor, can help track citation patterns within journals and determine which journals are highly-cited.
Impact Factor (IF) is perhaps the best known Journal Metric. IF is the average number of times, in the past two years, that articles from a journal have been cited in the Journal Citation Reports (JCR).
Impact Factor is just one metric used to measure a journal's impact. Additional metrics should be considered.
The impact factor is a measure of the frequency with which the average article in a journal has been cited in a particular year. The JCR also lists journals and their impact factors and ranking in the context of their specific field(s).
The h-index is an author-level metric that attempts to measure both the productivity and citation impact of the publications of a scientist or scholar. The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications.
The g-index is an index for quantifying scientific productivity based on publication record (an author-level metric). It was suggested in 2006 by Leo Egghe.
Altmetrics are statistics sourced from the social Web that can be used to help you understand the many ways that your work has had an impact with other scholars, the public, policy makers, practitioners, and more. They are useful supplementary measures of impact, best used in tandem with traditional measures like citation counts. Together, the two types of metrics can illustrate the full impact of your work.