Efforts to devise and use impact or influence evaluation metrics will continue because of the intense competition for funding on the part of investigators, one the one hand, and the limited resources available on the other. Such efforts are inevitable and in a sense necessary.
Difficulties arise when the metrics are applied with little appreciation of the assumptions on which they rest, or of the severely limited and qualified information they provide.
The search for a useful "second best" method of assessing impact relies on the professional literature as the best available substitute, assuming that all is well in scholarly publication. There is serious reason to treat such an assumption with reserve.
If evaluation metrics based on the analysis of the published literature lead in turn to the publication of "new" kinds of documents designed to blunt or even manipulate the metrics being used, such efforts may only result in the further compromise of the professional literature itself.
A good summary of measures considered here and of certain other techniques can be found at: