The research assessments of countries or institutions should reveal their contribution to the advancement of science. Taking into consideration the correlation that exists between scientific impact and number of citations, research assessments can be based on citation counts. However, it is crucial to perform the counts in the heavy tail of citation distributions. Following this heavy tail approach, all measurements performed in Spanish universities show that their research is inefficient because the proportion of highly cited papers is much lower than in the most scientifically advanced countries. The same conclusion is reached when considering the number of researchers in the Ioannidis, Boyack, and Baas lists of highly cited researchers.

13 pages, in Spanish, 1 figure, 5 tables