- almost all of the journals are in English
- and are published in Western Europe and the U.S.
- not all areas of study—especially within the humanities and social sciences—are represented,
- while others are under-represented in terms of their journals
- working papers are not included
- data is included from journals that publish original research as well as from review journals' review articles, each of which have very different citation patterns and behavior
- negative citations give false weight to the measurement of impact
- and citations from books are generally absent.
Many of these criticisms can be applied to other tools as well. In short, JCR and Web of Science are fine tools for certain subjects and their results should be combined with other analyses.