2.2 Hypothesis: Based on our experimental results as well as the results of others(Xi, Beguin et al. 1989; Zivelin, Rao et al. 1993; Brummel, Paradis et al. 2001), we hypothesize that the Fiix-PT may reflect anticoagulation and the antithrombotic effect of VKA at least as accurately as than the current PT based tests do (PT, P&P).