Optimal Designs of Studying Bioimpedance – Design for Nonlinear Mixed Effects Models

Bioelectrical impedance analysis measures the impedance to flow of an alternating electrical current passed through biological tissue. Such impedance measurements allow one to estimate fat-free body mass which is an accepted estimate for lean body weight, considered by some to be a better predictor of drug clearance in the obese than, for example, total body weight. D-optimal designs for nonlinear mixed effects bioimpedance models are explored. Despite the wide use of such models in this area, it is well-known that they have poor predictive performance at extreme frequencies. D-optimal designs that account for this variation, and also possible misspecification of initial parameter estimates, are found in an attempt to form practical and applicable designs.