How are determined the most cited researchers in Thomson Reuters?

In 2001, for the first time, a list was published to introduce more than 7,000 researchers who are best in one of the 21 key areas of science and social sciences, based on Essential Science Indicators used in the areas with the most citations. Thomson Reuters most recently has changed its approach in selection of top researchers. In this paper, after introducing the ISI as the basis for highly cited researchers, we introduce the highly cited researchers based on new method; and after comparison of current and former method, the highly cited researchers in Iran in 2014 and 2015 will be introduced.