We adopt a principled approach to defining who an expert is. An expert is someone who (a) writes consistently about a small set of tightly related topics; if you are an expert in everything, you are an expert in nothing, and (b) who has a loyal following that engages with her contents consistently and finds them useful, and © who actually expresses opinions on the topics he writes about rather than merely breaking the news.
Formulating the above criteria, and implementing it at scale, is a daunting big data task. Firstly we needed to form a rather comprehensive picture of the body of works published by authors that often write on many different outlets and at times under different aliases. Secondly, we had to create a dynamic topical model that learns the relationship between tens of thousands of topics by analyzing millions of documents. Thirdly, we had to come up with a formula that results in a stable, consistent, ranking, that is robust to fluctuations in publishing patterns and engagement data, yet is adaptable to allow in for new experts and their voices to be heard.