1. Curelator, Inc, Cambridge, MA, USA
2. Biostatistics and Data Management Core Facility, IDIBAPS (Institut d’Investigacions Biomèdiques August Pi i Sunyer), Hospital Clinic Barcelona, Barcelona, Spain
3. Biostatistics Unit, Faculty of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
4. Headache Group, Department of Neurology, Medical University of Vienna, Vienna, Austria