accuracy of Thomson data

Stephen J. Bensman notsjb at LSU.EDU
Thu Dec 20 16:36:47 EST 2007

I try to do some of this in the paper posted on Dr. Garfield’s Web site at:


You might want to look at the second half of the paper, where I discuss 
the Impact Factor in terms of Poisson lambdas, sampling variance, random 
error, etc.  The amazing thing to me, at least, is that despite all the 
random error and sampling variance, there is a remarkable stability of 
probability across time with Spearman rhos of 0.9 and above with high 
respectable correlations with Total Cites, library use, and expert 
ratings.  Most impact factors move up and down within extremely narrow 
limits across time.  I found a similar phenomenon in a paper just accepted 
by JASIST called “Distributional Differences of the Impact Factor in the 
Sciences vs. the Social Sciences: An Analysis of the Probabilistic 
Structure of the 2005 Journal Citation Reports.”   I no longer own the 
copyright and so cannot post it, but I suppose that I can let you read it 
on a private basis, if you’re willing to suffer the pain of reading it.  
There is much more to the Impact Factor than meets the eye, and it is an 
extremely good measure for many purposes, if of extremely doubtful use for 
ranking purposes in the vast bulk of the cases.   


Stephen J. Bensman, Ph.D.
LSU Libraries
Louisiana State University
Baton Rouge, LA   70803
notsjb at

More information about the SIGMETRICS mailing list