title: Sampling bias, sample size, ordinal regression model, and competing risk in evaluating association between ABO blood group and severity of liver fibrosis in Hepatitis C virus patients.
authors.affiliation: MD, MPH, PhD Candidate of Epidemiology, Minimally Invasive Surgery Research Center, Iran University of Medical Sciences, and Department of Epidemiology, Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Kabir