Journal impact factors ‘no longer credible’ | Times Higher Education

"Trickery by editors to boost their journal impact factor means that the widely used metric 'has now lost most of its credibility', according to Research Policy journal ... In the past two decades, the reliance on impact factors when deciding which academics are promoted or granted tenure has grown.  One of the most widely used impact factors is calculated by Thomson Reuters by dividing the average number of citations given to articles in a journal by the total number of papers. Normally the figure is calculated for articles published over the previous two years. 'Editors’ JIF-boosting stratagems – Which are appropriate and which not?', by Ben Martin, a professor of science and technology policy studies at the University of Sussex, lists a number of potentially suspect ways journals manipulate this figure ..."