Comment on "Parameter and structural identifiability concepts and ambiguities: a critical review and analysis".
Identifiability of a model for the glucose tolerance test, considered by Cobelli and DiStefano [Am. J. Physiol. 239 (Regulatory Integrative Comp. Physiol. 8): R7-R24, 1980], is shown to depend on the shape of the external perturbation. For systems with two or more inputs applied simultaneously, it is essential in Laplace transform identifiability analysis to examine the Laplace transform(s) of the observation(s) rather than the individual transfer functions, which are not measurable separately.
D005951:Glucose Tolerance Test; D008954:Models, Biological