Several experimental methods to measure ferroelectric hysteresis loops and to extract polarization values are compared for thin films with significant losses and different magnitudes of polarization. The analysis allows the determination of the most appropriate frequency range and technique to extract reliable values of the remanent polarization in materials with low polarization and high leakage. Examples include multiferroic YMnO(3) and Bi(0.9)La(0.1)NiMnO(6) thin films. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3555098]