Journal-level

• Journal Impact FactorFormula: total number of citations/total number of publications during past 2 yearsFor example, the 2017 Impact Factors (released in 2018) used the following calculation:

  Number of citations received in 2017 to content published in Journal X during 2015 and 2016*,* divided by the total number of articles and reviews published in Journal X in 2015 and 2016*.*Variant: 5-year impact factor

• EigenfactorThe Eigenfactor measures the influence of a journal based on whether it’s cited within other reputable journals over five years. A citation from a highly-cited journal is worth more than from a journal with few citations.Formula: Number of citations in one year to content published in Journal X in the previous five years (weighted), divided by the total number of articles published in Journal X within the previous five years.

• Article Influence ScoreThe Article Influence Score is a measure of the average influence of a journal’s articles in the first five years after publication. A score greater than 1.00 shows above-average levels of influence.Formula: (0.01 x Eigenfactor of Journal X) / (number of articles published in Journal X over five years / the number of articles published in all journals over five years).

• CiteScoreCiteScore is the ratio of citations to research published.Formula: Number of all citations recorded in Scopus in one year to content published in Journal X in the last four years / the total number of items published in Journal X in the previous four years.

• SNIP - Source Normalised Impact per PaperIt measures citations received against citations expected for the subject field, using Scopus data.Formula: Journal citation count per paper / citation potential in the field.

• SJR - Scimago Journal RankThe SJR aims to capture the effect of subject field, quality, and reputation of a journal on citations. It calculates the prestige of a journal by considering the value of the sources that cite it, rather than counting all citations equally.

  Each citation received by a journal is assigned a weight based on the SJR of the citing journal. So, a citation from a journal with a high SJR value is worth more than a citation from a journal with a low SJR value.Formula: Average number of (weighted) citations in a given year to Journal X / the number of articles published in Journal X in the previous three years.

Paper-level

• Altmetric Attention ScoreAltmetric monitors each online mention of a piece of research and weights the mentions based on volume, sources, and authors. A mention in an international newspaper contributes to a higher score than a tweet about the research, for example.The Altmetric Attention Score is presented within a colorful donut. Each color indicates a different source of online attention (ranging from traditional media outlets to social media, blogs, online reference managers, academic forums, patents, policy documents, the Open Syllabus Project, and more). A strong Altmetric Score will feature both a high number in the center, and a wide range of colors in the donut.
• Paper Impact EffectivenessThe PIE combines the total number of citations (C), the total number of reads (R), and the age of a paper in years where PIE = (C/R)/A (A = current year - publication year).Original publication
• **Paper Impact Factor (in-house TRIP factor)**What determines the impact of a paper?1. Reproducibility2. Applicability (i.e. does it have a direct industrial/policy application?)3. Research topic (i.e. is it a high-priority research topic?)4. Scale (if applicable, i.e. local, regional, global)5. Accessibility (i.e. is it open access or not?)6. Cross-disciplinarity7. Diversity in authorship

Author-level

• The h-index or Hirsch index - quantifies an author’s scientific research output. Reflects both the number of publications and citations of a researcher. Definition: h is the number of papers that received at least h citations. For example, an author with an h index of 24 has published 24 papers each of them being cited at least 24 times.
• The g-index is a variant of the h-index that gives more weight to highly-cited articles. Original publication
• The e-index The e-index is the (square root) of the surplus of citations in the h-set beyond h2, i.e., beyond the theoretical minimum required to obtain a h-index of 'h'. The aim of the e-index is to differentiate between scientists with similar h-indices but different citation patterns.Original publication
• The AWCR Average Weighted Citation Rate The AWCR measures the average number of citations to an entire body of work, adjusted for the age of each individual paper.Original publication
• The multi-authored h-index - accounts for shared authorship of papers.Original publication

Overall impact of research

• The Payback FrameworkAssesses outcomes of Health Science research - originally published by Buxton and Hanney (1994). The Payback Framework Explained
• Productive interactionsBased on the widely held assumption that interactions between researchers and stakeholders are an important pre-requisite to achieving impact - Original publication