Apex Index: A Hit-based Metric for Measuring the Impact of Papers and Scientists

In this study, we introduce a novel metric called the Apex index, which is a hit-based measure for assessing the impact of scientific publications and scientists. The basic principle of the Apex index involves quantifying the number of hit papers that cite the focal paper. Specifically, we identify the top 1% most highly cited papers in a given field and year as the hit papers. We then calculate the Apex index for all publications in the MAG database, which contains approximately 200 million documents. Our study reveals that Nobel Prize-winning papers display a higher Apex index compared to other papers, and Nobel laureates exhibit a higher Apex index than their peers. Moreover, we demonstrate that the Apex index has a higher convergent validity in evaluating scientists and identifying laureates. Overall, the Apex index presents a valuable and effective tool for assessing the impact of scientific publications and researchers.