Sometimes the impact factor outshines the H index

Recently, Jeang [1] argued forcefully for the use of individualized citation metrics instead of measures of journal quality for evaluation purposes. Before the age of personal computers, so Jeang argues, judging an article by the quality of the journal was almost inevitable; but as individualized citation statistics have become readily available, it appears outdated to "judge a book by its cover". We agree with Jeang that individual merit is suitably measured by individualized citation metrics, which also predict scientists' future success well [2]. But we also contend that "judging a book by its cover" (i) is deeply engrained in human nature [3], (ii) can be adaptive because outward appearance is often a probabilistic cue to some hidden quality [4,5], (iii) and is often without alternative. Imagine you want to decide which new articles to read outside your narrow field of specialization. How can you decide which ones are worthy of your time when citation frequencies are not yet available? You may infer article quality from an individualized citation metric like the H index of the author (with H being the largest number of publications of an author that have been cited at least H times); alternatively, you may base your inference on a measure of journal quality like its impact factor (IF, which reflects the average citation frequency of articles from a particular journal).Previous research suggests that the IF may outperform the H index in predicting an article's number of citations, which is often used as a proxy for article quality [2,6,7]. Not because IFs work particularly well – as Jeang [1] correctly noted, citation frequencies vary greatly for articles in the same journal – but because the H index should be completely unsuitable for this specific task. This is because authors who publish the most highly cited publications also publish the highest number of ignored publications [6]. As a consequence, a counter-intuitive equal-odds rule [7] is at work, whereby a