IDENTIFIABILITY: THE FIRST STEP IN PARAMETER ESTIMATION.

Hypothesis testing in work on membrane transport, receptor reactions and metabolic pathways involves the development of kinetic models and estimation of their parameters. The latter includes estimation of parameters not directly observable, i. e. , inaccessible parameters. Given a model, a major goal in the design of experiments is to devise experiments that allow one to estimate the needed parameters. For any given experiment, one has to determine the required parameters; that, is the identifiability problem. Identifiability is an a priori problem and can be tested before doing the experiments. A direct approach is by way of the relation between the basic parameters of the model and experiment and the observational parameters. The application of this theory will be illustrated with a few examples, starting with Michaelis-Menten kinetics.