The methodology for inclusion is to take the upper percentiles based on citation counts of all articles indexed in the Scientific Citation Databases in a 10-year, rolling time period. Each article in the data is assigned to one or more of 21 categories, based on the ISI classification of the journal in which the article was published. Those on the Highly Cited Researcher list constitute (in the terms stated above) the 250 most cited researchers of the specified time period.
The publication list and biographical details supplied by the researchers are freely available on line, although general access to the ISI citation database is by subscription.