Theoretical investigation, model test and analysis of the data available all suggest that the research on complex resistivity spectra is subject to certain limitations if only amplitude spectrum and phase spectrum are used. As a remedy, an integrated utilization of amplitude, phase as well as real and imaginary component spectra makes it possible to derive the reliable initial values of such spectral I. P. Parameters as r, m and c by means of simple procedures in fitting and inversion computations, which in turn will contribute to a further shortening of the fitting and inversion process.