In an article in Biomedical Digital Libraries (December 
2005), authors Peng Dong, Marie Loh, and Adrian Mondry 
demonstrate that online availability of articles greatly 
influences the impact factor. They studied document sets 
that included some online articles and some not available 
online. They learned that impact factors were increased for 
journals whose text was freely available online. They 
expect that this effect will increase as more powerful 
search engines penetrate deeper into the scholarly world 
and allow researchers to find relevant articles in an 
instant.