Yale recently was ranked fourth among America's top research universities when "citation impact" was used to assess scientific performance. Citation impact was measured by calculating the average number of times an institution's published research papers were cited by other scientists worldwide.

The survey, which was conducted by the Philadelphia-based Institute for Scientific Information, covered the five-year period from 1993 through 1997 and spanned the biological, physical and social sciences.

"This ranking, unlike other measures of excellence that strongly favor institutions with large departments, assesses the impact per faculty member," says Pierre Hohenberg, deputy provost for science and technology. "Yale's strong performance underscores the extent to which each member of Yale's faculty contributes to research and scholarship, thereby assuring that the majority of students will benefit from Yale's preeminence, not just a few who happen to come into contact with superstars."

The leading universities, based on the number of times their citation impact placed them among the top 10 in each of 21 scientific fields, were Harvard, which appeared in 17 of the 21 rankings, followed by Stanford with 13 top-10 showings, Caltech with 11, and Yale and the University of Michigan with nine each. (Ties were broken by calculating which university had a higher overall ranking within the top 10). Following in fifth place was MIT with eight top-10 showings, the University of California, Berkeley, with seven, and the University of Washington, the University of California at Santa Barbara and Cornell University with six each.

Here is how Yale ranked in the nine fields in which the University was among the top 10: second in law and in psychology and psychiatry, fourth in immunology and in economics and business, fifth in physics and chemistry, eighth in engineering and neuroscience, and 10th in math.