1 From the Department of Biostatistics (G.R.C.), University of Alabama at Birmingham; and the Departments of Clinical Neurosciences (M.W.K.) and Community Health Sciences (M.W.K.), University of Calgary, Canada. cutterg@uab.edu.
2 From the Department of Biostatistics (G.R.C.), University of Alabama at Birmingham; and the Departments of Clinical Neurosciences (M.W.K.) and Community Health Sciences (M.W.K.), University of Calgary, Canada.