Neal D Goldstein1, Ghassan B Hamra2, Sam Harper3. 1. From the Department of Epidemiology and Biostatistics, Drexel University Dornsife School of Public Health, Philadelphia, PA. 2. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD. 3. Department of Epidemiology, McGill University Centre on Population Dynamics, Biostatistics and Occupational Health, Montreal, QC.