Hi Pharsight Modellers, I have question regarding to the calculation of condition number in phoenix. In the user guide, it states that when the condition number exceeds 1E+6, then the model is probably overparameterized. However, I recalled that when using NONMEM, the criteria is <1000, (it happens to be square root of 1E+6). I wonder how the difference just because the calculation? Thanks, Shu-Pei
Shu-Pei, as I understand the condition number is a property of the actual problem so as a general rule of thumb, if the condition number is less than = 10^number of parameters then it is probably well-conditioned. However I’ve seen it exceed this and still been a good fit by other metrics so I wouldn’t look at it in isolation. Simon
Hi, Simon, Thanks for your response for sharing the general rule of thumb of looking at condition number. I also agree that it is just one of many diagnostic indicators for accessing the model.\ Thanks again, Best, Shu-Pei