On behalf of a sponsor company, C3 Research Associates is conducting a clinical study on the effect of pharmacogenetic testing for dosing of warfarin. The study is a prospective, randomized, blinded study. The patient population includes individuals that are new to warfarin therapy. Adverse bleeding events of patients whose dose is determined using pharmacogenetic information will be compared to adverse bleeding events of patients whose dose is determined via standard methods. The information in this survey will be used to help us evaluate potential study sites. If you have any questions, please contact Ron Carozza at C3 Research Associates (firstname.lastname@example.org, 206-686-4644 x1). C3 Research Associates is responsible for site selection. Please do not contact the study sponsor directly.