IF is widely accepted now,however it could be debated worthiness. Citation index of an article would be ideal.

IF is widely accepted now,however it could be debated worthiness. Citation index of an article would be ideal.

SJR and Thomson-Reuters IF is certainly a crude way to measure impact. They vary substantially by discipline, so that reputable humanities journals have low or no impact factor, while in the biomedical domain impact factors are normally much higher. They obviously change every year. Editorial strategy can also affect the impact factor, if editors make their decision based on the predicted number of citations rather than the scientific merit of articles. So it would be incorrect the simply say that a journal with impact factor 3.5 is better than a journal with impact factor 3.1.

But the impact factor does give some general idea about the reputation of the journal, especially if you are not familiar with the specific journal. If you are familiar with the journals in your discipline you would normally know which journals are the more important ones and would not need the impact factor to know. If you are not familiar with the journals, you can use the IF for rough approximation.

But as for your question, IF measures the reputation of journals, not individual researchers. For individual researchers there are other metrics, normally based on citations, such as the h-index, which is in itself a rough approximation of the true impact of a researcher on his or her field.

In addition to what has been said, there are studies that inferred about the "empirical" bias of most journals (I am primarily talking about journals in marketing discipline). This is how an editorial policy can eye on citations and not on the innovative conceptual ideas that is subject to highly differing interpretation by different reviewers. Interestingly, there are a few journals that would accept only conceptual papers, but you will see uniqueness in their publications coming at a cost of lower citations. Some journals would politely and subtly indicate to cite their related past articles. In the long run, the speed at which the citation will pick up is a function of the discipline concerned. Language could be another barrier. For example, a German journal published in English will have higher probability of having higher impact factor than the same journal if it were published in German language. That is another issue of assessing research intensity of specific national boundaries. Same applies to Japanese and Russian journals. I believe some researchers can refer more examples in this regard. Moreover, the choice of researchers becomes limited by the fact that there is not a long list of social science or business journals when it comes to impact factor listing, when compared with natural science or health related journals. 

However, in the backdrop of growing number of journals in Beall's List (although there are some criticism of Beall's List as well), the impact factor could serve as a general guideline to assess the initial quality of the journal, without being overwhelmingly obsessed with the figure reported. 

High IF journals enjoy prestigious and worth among other journals with low IF. However, high IF journals looks like a basket of fruits with mixed quality and standard of fruits. There is need for more index weight  to be given to an article individually, because there are some journals which publish a lot of articles while some others do limited, so obviously more the article in any journal the more will be impact.  

There are 185 journals in management area list of THOMSON REUTERS IMPACT FACTOR ..cross checked with 45 Journals rated by financial times and found no relation...for example Journal of Business Ethics (springier) has only 1.36 Impact Factor and ranked low in the list of 185..

.Rank Journal 2014 Impact Factor Five Years Impact Factor Publisher Hyperlink

1 Academy of Management Annals 7.769 10.866 Academy of Management http://aom.org/annals/

2 Academy of Management Review 7.475 10.736 Academy of Management http://aom.org/amr/

3 Academy of Management Journal (AMJ) 6.448 9.812 Academy of Management http://aom.org/AMJ/

4 Journal of Management 6.071 Sage jom.sagepub.com/

5 Strategic Management Journal 5.9 9.0 Wiley http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-0266

6 MIS Quarterly 5.311 8.490 http://www.misq.org/about/

7 Journal of Information Technology 4.525 5.348 Palgrave http://www.palgrave-journals.com/jit/index.html

Dear Mark, dear all, many researchers are questioning the credibility of the impact factor.  But some of us have administrators who consider that as important.  So there is some silent pressure.  So far, I published on local journals that do not have impact factors, although some are indexed in Scopus, and the peer review is great and good to improve the papers.  But I should try open access journals with some impact factor, just for the experience, bearing in mind that the credibility is open to question.  Thanks.

Sometimes, editors try to "boost" their journal's impact factor: look, for instance, at this editorial by B.R. Martin on such ways: http://www.sciencedirect.com/science/article/pii/S0048733315001390 . Also, look at this article on other problems associated with impact factors: http://www.editage.com/insights/why-you-should-not-use-the-journal-impact-factor-to-evaluate-research

Thus, it is not enough to focus only on the journal's impact factor, other aspects should be considered, too.

Dear @Mark, thanks for sharing the question. Of course, any metrics has its own advantages and disadvantages, so you may say that JIF suffer from reliability, lack of objectivity.... Up to now we did not have better metrics for Journals.

New efforts have been made in November regarding ESCI. Emerging Science Citation Index. "Science Citation Index Expanded™, accessed via Web of Science™ Core Collection, provides researchers, administrators, faculty, and students with quick, powerful access to the bibliographic and citation information they need to find research data, analyze trends, journals and researchers, and share their findings..."

http://thomsonreuters.com/en/products-services/scholarly-scientific-research/scholarly-search-and-discovery/science-citation-index-expanded.html

http://thomsonreuters.com/en/products-services/scholarly-scientific-research/scholarly-search-and-discovery/science-citation-index-expanded.html#

IF calculated by ISI Thomson Reuters is universally acceptable.