Abstract The Cole-Cole dispersion approximates the behavior of inductive coupling over only a part of the frequency range. We show that the interaction between the induced polarization (IP) and inductive coupling (IC) effects will, in general, be more complicated than a multiplication of two Cole-Cole dispersions representing the separate IP and IC effects. The inversion of published data shows that the time constant (tau 1 ) of the IP effect is often a poorly defined parameter. Hence, small changes in the parameters used to approximate inductive coupling by a Cole-Cole dispersion can produce very large changes in the calculated value of tau 1 . From these considerations, guidelines are developed to show when the Cole-Cole dispersion may be successfully used to approximate inductive coupling and define tau 1 .