The present work demonstrates that the representation of log(tg(delta)) vs, log(f) may be best suited to reveal the bulk, grain boundary, and electrode contributions of impedance spectra, and to extract the relevant parameters. Alternative representations of Z" vs. Z', log(Z") vs. log(f), log(M") vs, log(f), and log(A") vs. log(f) often have a limited applicability. The log(tg(delta)) vs. log(f), and log(A") vs. log(f) plots show peaks or minima at frequencies that are somewhat displaced relative from the true relaxation frequencies, or transitions from the electrode to grain boundary, or grain boundary to bulk contributions. Suitable criteria are proposed to account for these differences.