Speaker 1: In this episode, we will explain to you an author-level metric called H-index. Short for Herschd index, the H-index was suggested by American physicist Jorge Herschd, who was looking for a simple metric that can help researchers measure simultaneously the quality and quantity of their scientific output. In other words, impact as well as productivity. The H-index can be defined as an author having H articles that have been cited at least H times. Let's take a look at a real example by going into Scopus. Here is the author page of Professor Jonathan Wong. We can see that he has an accumulated publication count of 252 that has been cited 8,857 times. Here we can see that Professor Wong's H-index is 53. It means that out of Professor Wong's 252 publications, 53 articles have been cited at least 53 times, making 53 his H-index. Apart from Scopus, H-index can also be obtained via Web of Science. Google Scholar also calculates an author's H-index via their citations profile feature. If we look at Professor Wong's Google Scholar profile, we can see that his H-index is a little higher, at 66. And in Web of Science, the number is a little lower, at 46. The reason why these numbers vary is because each database covers different journals and time periods. There is also the problem of author-variant names and thus split profiles, so you need to be aware of such inconsistencies. Obviously, a scholar's impact can't be summed up with a single number. Like many metric tools, the H-index has limitations and shouldn't be used as a direct measure of quality. Here are a few important points to note. Compare only researchers of similar career length and in similar fields. It shouldn't be used as a direct measure of quality. It is best used in conjunction with other metrics. We hope you have now gained a good understanding of what H-index is. Watch our other episodes of the 2-Minute Metrics to find out more.