Dear all, I would like to simulate a study in which the prevalence of an event is 1% (p = 0.01), and the risk of the event is associated with two risk factors: x1 and x2. The odds ratio per standard deviation increase in x1 is 1.8 (95% CI: 1.1 to 2.8), and the odds ratio for x2 being present is 2.1 (1.8 - 3.1). x1 is a continuous variable with normal distribution (mean = 1.0, SD=0.10). x2 is a categorical variable (with two values 0 and 1), and the prevalence of x2=1 is around 10%. I have looked at the codes given in Design package, but I am not sure how to simulate the prevalence. Any help is highly appreciated. Regard, Nguyen ____________________________ Nguyen Dinh Nguyen Bone and Mineral Research Program Garvan Institute of Medical Research St Vincent's Hospital 384 Victoria Street, Darlinghurst Sydney, NSW 2010 Australia Tel; 61-2-9295 8274 Fax: 61-2-9295 8241 E-mail: n.nguyen@garvan.org.au [[alternative HTML version deleted]]