Journal Metrics Overview - Wiley Online Library

Impact Factor

The Impact Factor is the average number of times
articles from the journal published in the past two years have been
cited in the JCR year. The Impact Factor is calculated by dividing the
number of citations in the JCR year by the total number of articles
published in the two previous years. Also see: "Understanding Impact Factors"

5-Year Impact Factor

The 5-year Impact Factor is the average number of times
articles from the journal published in the past five years have been
cited in the JCR year. It is calculated by dividing the number of
citations in the JCR year by the total number of articles published in
the five previous years. Also see: "Four Ways of Measuring Impact"

Altmetrics

(Any source)

Altmetrics go beyond more traditional citation metrics
to measure social visibility around scientific articles. These metrics
are based on a broad spectrum of indicators, such as tweets, blog
mentions, news media, social bookmarking, article views, and downloads.
Also see: "Using Altmetrics and Social Media for Research and Networking"

Eigenfactor

The Eigenfactor is based on weighted citations in the
JCR year to papers published within the previous 5 years. Citations are
weighted according to the prestige of the citing journal, with citations
from highly ranked journals making a larger contribution to the
Eigenfactor than those from poorly ranked journals. Also see: "The Eigenfactor and Other Metrics – Plus Ça Change"

Google Scholar Metrics

The main Google Scholar journal metric is the H5 index
and is based on articles published in the last 5 complete calendar
years. This is similar to the h-Index but also includes the top cited h
articles (h-core) and the median of the citation counts (h-median). Also
see: "Demystifying Google Scholar Search and Results"

h-index

Web of Science, Google Scholar, or Scopus

The h-index attempts to measure the productivity and citation impact of the published body of work of an author. The h-index indicates the number of papers, h, that have been cited at least h times (e.g. an h-index
of 15 means that 15 papers have been cited at least 15 times each.)
Note: Due to variations in citation coverage between databases, each
source may determine a different value of the h-index for each author. Also see: "Four Reasons Why the h-index is Here to Stay"

Immediacy Index

The Immediacy Index is the average number of times an
article is cited in the year it is published. The Immediacy Index is
calculated by dividing the number of citations to articles published in a
given year by the number of articles published in that year. Also see: "How to Navigate the World of Citation Metrics"

SJR

The SCImago Journal Rank (SJR) Indicator is based on
weighted citations in Year X to papers published in the previous 3
years. Citations are weighted by the prestige of the citing journal, so
that a citation from a top journal will have more impact than a citation
from a low-ranked journal. Also see: "Metrics Alternatives to Altmetrics?"

SNIP

The Source Normalized Impact per Paper (SNIP) measures
average citations in Year X to papers published in the previous 3 years.
Citations are weighted by the citation potential of the journal’s
subject category, thereby making the metric more comparable across
different disciplines. Also see: "Can We Do Better Than Existing Author Citation Metrics?"