JCR also reports the Eigenfactor Score.
It is an effort to weight the sources of those citations, so a citation
for a top-tier journal is weighed more. This involves a complicated computation. The Eigenfactor Score uses data from JCR but
measures the percentage of time that a model researcher following
citations visits that journal.
The Article Influence Score, also reported in JCR, is more comparable to the impact factor. It scales Eigenfactor score by the number of
articles published by the journal.