Superboring: Impact Factors

Dr. LB, a bright young clinical epidemiologist, began to discuss the role of Impact Factors in publications yesterday.  Which obviously begs the question, um..."What's an Impact Factor?" Well, simply put it's the ranking of scientific journals based on citations.  The simple way to calculate it is:

number of citations/number of articles

SCI-BITES has a pretty comprehensive list of Impact Factors as does Dr. Popescu.  And clearly when one talks of such lists, one always wants rankings.  So here are a few from SCI-BITES:

By country (again showing the fallacy of US medical xenophobia, the US is not #1):

Rank	Country	Papers 1993-2003	Avg. citations per paper
1	Switzerland	142,982	13.24
2	United States	2,799,593	12.63
3	Netherlands	202,184	11.33
4	Denmark	79,929	11.14
5	Sweden	158,136	10.85
6	Scotland	96,571	10.75
7	England	619,707	10.74
8	Canada	370,928	10.25
9	Finland	74,106	10.17
10	Belgium	103,181	9.74

and for the most commonly read journals around these parts (from 2001):

• Annals of Internal Medicine - 8.25
• BMJ - 3.64
• JAMA - 6.03
• Lancet - 12.41
• New England Journal of Medicine - 19.68
• Pediatrics - 2.72

oh and the Journal of Healthcare for the Poor and Underserved - um...it didn't quite make the list yet...