The state-of-the-art is reviewed for the use of measurement models for assessing the stochastic and bias error structure of impedance measurements. The methods are illustrated for published impedance data that contain both capacitive and inductive components. This systematic error analysis demonstrates that, in spite of differences between sequential impedance scans and the appearance of inductive and incomplete capacitive loops, the individual data sets represented a pseudo-stationary system and could be interpreted in terms of a stationary model. (C) 2004 Elsevier B.V. All rights reserved.