Chapter 9: An Extended H–Index: A New Method to Evaluate Scientists’ Impact

Researcher evaluation is increasingly popular and important in the scientific community. Measures to assess the scientific impact of a researcher have been proposed through lots of scientists’ efforts. Among various methods, the h-index is the most widely used, in that it incorporates the quantity and quality of a scientist’s productivity, and it can be conveniently used. Nevertheless, there are some drawbacks to using the h-index. In order to remedy some disadvantages of the h-index, scientists have proposed some h-type indices. However, few indicators take account of the quality of citations of a paper. Most indices treat all citations equally. But the citation quality should be a key factor in the evaluation result. A paper must be valuably cited by a high quality paper, but it does not illustrate its value cited by marginal articles. We then propose a new index, the extended h-index (EHI), which considers the role of citation quality in evaluating a researcher’s impact. We analyze the difference between the EHI and other four h-type indices, and explore their relationships using Spearman correlation analysis and factor analysis. The results show that the EHI can effectively evaluate the impact of a researcher. The EHI provides a new way of thinking that any h-type indicators can apply; that is, regarding the number of the high quality citation as an important criterion to measure the quality of a paper, and then evaluate the impact of a researcher.