The assessment of research publications is an important part of the research process. There are plenty of methodologies in practice, but three most common methods of assessing the merit of a research paper are subjective post-publication peer review, citations gathered by a research paper, and the impact factor (IF) of the journal in which the research was published.
The impact factor relates to a specific time period; though it is possible to calculate it for any desired time period. The impact factor is used to compare different journals within a same field. It is possible to examine the impact factor of the journals in which a particular person has published articles.
The use of impact factor is widespread, but debated because of its irrelevant use in evaluating individuals because there is a wide variation from article to article in a single journal. Still Impact factors have a great, but controversial, influence on the way published scientific research is perceived and evaluated.
Another reason it is debatable because some companies are producing false impact factors and the effect of policies that editors may use to improve their impact factor which is detrimental to readers and writers. Another factor to be considered is impact factor might not be consistently reproduced in an independent audit.
Another criticism focuses on the effect of the impact factor on response of scholars, editors and other stakeholders.
Many research foundations have published and suggested new guidelines to evaluate journals like the International Council for Science Committee on Freedom and Responsibility in the Conduct of Science has issued a statement on publication practices and indices and the role of peer review in research assessment, advising many possible solutions to this issue—like considering a limited number of publications in a year to be taken into consideration for each researcher, or even penalizing researcher for a excessively large number of publications per year.
Emphasis has been raised on increasing importance of numerical indicators such as the h-index. Other to name are immediacy index, cited half-life, aggregate impact factor, source normalized impact per paper, page rank algorithm etc.
The methods shared above apply only to journals, not individual articles or scientists.
Article-level metrics such as H-index measure impact at an article level instead of journal level. Other more general alternative metrics include article views, downloads, or mentions in social media and tweet, thus introducing a “Twimpact factor” and Twindex. Public Library of Science introduced another method called article-level metrics.