Are citation rates the best way to assess the impact of research?

"The United Kingdom’s Medical Research Council (MRC) - the equivalent of Australia’s National Health and Medical Research Council - recently released its 2014-15 economic impact report, details of which make for interesting reading. Since 2006, research funded by the MRC resulted in more than 94,000 publications, 63,000 of which (67%) were peer-reviewed. The traditional starting point for considering the scientific impact of research are its citations. This is how many other research papers and editorials subsequently cite a given paper into the future or in a given number of years since publication. Different numbers of researchers are involved in different fields of research. So when a relatively small number of scientists work in a study area, even if they write a spectacularly important paper, it can still receive a small fraction of the citations a comparably important paper receives in an area where more researchers are involved. It would be unreasonable and misleading to conclude that a leading researcher in a small field had less scientific impact than one in a big field. Also, as can be seen from this table, a paper that has been published for a short time has naturally had less time to be cited than one that has been out for longer ..."