The raw impedance data for the LA-GEIS measurements are shown in Fig. , while the interpolated touchdown points are shown in Fig. . Two factors must be accounted for to accurately fit the LA-GEIS data to the BV model. First, the RMS current, not the current excitation amplitude, must be used to fit the Rct versus current data; otherwise, α will be underestimated by a factor of √2 and I0 will be overestimated by a factor of √2. Second, it must be ensured that the harmonic distortion of the impedance signal is sufficiently low to satisfy the condition of linearity.