  Measuring the efficiency of scientific research activity presents critical
methodological aspects, many of which have not been sufficiently studied.
Although many studies have assessed the relation between quality and research
productivity and academic rank, not much is known about the extent of
distortion in national university performance rankings when academic rank and
the other labor factors are not considered as a factor of normalization. This
work presents a comparative analysis that aims to quantify the sensitivity of
bibliometric rankings to the choice of input, with input considered as only the
number of researchers on staff, or alternatively where their cost is also
considered. The field of observation consists of all 69 Italian universities
active in the hard sciences. Performance measures are based on the 81,000
publications produced during the 2004-2006 triennium by all 34,000 research
staff, with analysis carried out at the level of individual disciplines, 187 in
total. The effect of the switch from labor to cost seems to be minimal except
for a few outliers.
