Dear friends, I log transformed the plasma concentrations in my data and I am using this log transformed data as my dependent variable (DV). I imputed the BQLs to LLOQ/2, which is my case is (1/2=0.5). The natural log of 0.5 is negative which mean that I have negative values in my DV column. While the parameter estimates look somewhat reliable, I have negative points plotted in the diagnostic plots such as DV vs PRED, DV and PRED vs TIME, etc. My questions are- 1. What is the best way of dealing with <1 DV/plasma concentration values while transforming into natural logarithm? 2. In my situation discussed above, where I have negative DV values in my data, has the NONMEM ignored or considered the negative numbers when estimating the parameter values?
Thank you, Manu -- *With regards-* *Manushree Bharadwaj, BVSc, PhD Candidate* *Graduate Teaching Associate* *Department of Physiological Sciences* *Center for Veterinary Health Sciences* *Oklahoma State University* *Stillwater, OK-74074*
