Simuni T, Long JD, Caspell-Garcia C, Coffey CS, Lasch S, Tanner CM, Jennings D, Kieburtz KD, & Marek K on behalf of the PPMI InvestigatorsAnnals of Clinical and Translational Neurology. 2016 May 17; 3 (7) 482-494. PubMed: PMC4931714Projects: PPMI Statistics Core