What is considered a good impact factor?
The higher the impact factor, the more highly ranked the journal is; however, opinions vary widely as to what constitutes a "good" impact factor.
In 2011, the Journal Citation Reports (JCR) database assigned impact factors to 8,836 journals. The table below shows the number and percentage of journals that were assigned impact factors ranging from 1 up to 30, for both one-year and five-year periods. As shown, only 20 journal titles, or 0.2% of the journals tracked by JCR, have a 2011 impact factor of 30. Only 151 journals have a 2011 impact factor equal to or greater than 10, which is the top 1.8% of journals with impact factors. 8,185 journals have a 2011 impact factor below 10.
UST does not subscribe to Journal Citation Reports. However there is some impact factor data for journals found at Cabell's here http://www.cabells.com/
For more information on impact factors and how they are produced, review Arizona State University Library's online guide, Citation Research.
Credit for this answer:
The Staff at the MD Anderson Cancer Center Research Medical Library