From: "jiang zhigang" jiangzhigangchn@hotmail.com Subject: [NMusers] How can I determine cl=theta1 or v=theta1? Date: Tue, 08 Aug 2006 22:18:24 +0800 Dear,all, The nonmem guide said,for ADVAN1 TRANS2, NONMEM requires code for CL and V. then, How can I determine cl=theta1 or v=theta1? If I choose cl=theta1 and v=theta2,k =cl/v=theta1/theta2; but , if I choose v=theta1 and cl = theta2,then k=cl/v= theta2/theta1, So the value of k will be entirely different at last! e.g. ,let theta1=4 theta2=2,I'll get 2 different results respectively! cl=theta1=4 v=theta2=2, k =cl/v=theta1/theta2=4/2=2 another, v=theta1=4 cl=theta2=2,then k=cl/v= theta2/theta1=2/4=0.5 Look,This is my puzzle! Can you give me some directions? Thank you very much! _______________________________________________________ From: "NIYI ADEDOKUN" niyiadedokun@hotmail.com Subject: RE: [NMusers] How can I determine cl=theta1 or v=theta1? Date: Tue, 08 Aug 2006 15:00:39 +0000 Hi, Think of it this way: CL and V and K are primary parameters hence they have "fixed" values. Your thetas are just a reparameterization of the "fixed" parameters. In other words it really does not matter which you call theta1 or theta2 because at the end of the day when you do get your results theta1 and theta2 will representy what you had initially coded them. Hence assuming that CL=4 and V=8 and you had decided to code CL=theta1 & V=theta 2 then since K=CL/V=theta1/theta2 =0.5. if you decided to code CL=THETA2 & V=THETA1 then k=theta2/theta1=CL/V=0.5. I hope this helps. _______________________________________________________