1 Aggregator: A machine learning approach to identifying MEDLINE articles that derive from the same underlying clinical trial by Weixiang Shao 1 , Clive E. Adams 2 , Aaron M. Cohen 3 , John M. Davis 4 , Marian S. McDonagh 3 , Sujata Thakurta 3 , Philip S. Yu 1 and Neil R. Smalheiser* 4 Departments of 1 Computer Science and 4 Psychiatry, University of Illinois at Chicago, Chicago, IL 60612 USA; 2 Division of Psychiatry, University of Nottingham, Nottingham, UK; 3 Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, OR USA; USA *neils@uic.edu, 312-413-4581