WebMD Editors determine the topics and placement on our lists in several ways. We evaluate our user activity, analyze population statistics available through government agencies and professional organizations, and in some cases use editorial or programming judgment. The topics are not ranked by most popular to least popular, are of relatively equal weight, and may appear simply alphabetized or numbered for your ease. If a sponsor or advertiser on WebMD happens to be affiliated with a topic on one of our lists, it is purely coincidental. Nothing should be implied by the topics or order of the list except that all the topics generate the most interest on WebMD or our editors and programmers have selected them.