Figure 7.

Uncertainty propagated in the model output caused by variation of two input parameters k_a and k_e. The uncertainty bands are the 2δ uncertainty of the model output (δ is the standard deviation of the model output). Variations in k_a and k_e are derived from the lognormal probability distributions (defined by Equation 7), the standard deviation is 0.2 (Top) Model output uncertainty due to k_a. (Bottom) Model output uncertainty due to k_e. Peak of each curve corresponds to C_max at T_max. Curve up to T_max is absorption phase and curve after T_max is elimination phase. Uncertainty in k_a dominates absorption phase whereas uncertainty in k_e dominates the elimination phase for all biomarkers. Time intervals of greatest uncertainty depend on the specific values of k_e and k_a. Note that the x-axis has been expanded or compressed depending on the half-life of the biomarker. Confidence limits provide insight as to when the uncertainty about k_a or k_e causes greatest uncertainty about biomarker level C_p.