Here is an excerpt from this article by Peter Lawrence:
Modern science, particularly biomedicine, is being damaged by attempts to measure the quantity and quality of research. Scientists are ranked according to these measures, a ranking that impacts on funding of grants, competition for posts and promotion. The measures seemed, at first rather harmless, but, like cuckoos in a nest, they have grown into monsters that threaten science itself. . . . The journals are evaluated according to impact factors, and scientists and departments assessed according to the impact factors of the journals they publish in. Consequently, over the last twenty years a scientist’s primary aim has been downgraded from doing science to producing papers and contriving to get them into the “best” journals they can. Now there is a new trend: the idea is to rank scientists by the numbers of citations their papers receive. Consequently, I predict that citation-fishing and citation-bartering will become major pursuits. . . .