We present a method to determine the two-dimensional 2D distribution (Formula presented) of the relaxation time (Formula presented) using an inversion of temperature-dependent broadband dielectric data. In contrast to the usual evaluation of 1D distributions (Formula presented), the 2D analysis reveals whether the broadening of a relaxation peak has its physical origins in a variation of the activation energy (Formula presented), or the preexponential factor (Formula presented) or both. A study of the (Formula presented) relaxation of a polymer blend demonstrates the validity of the analysis. We compare the distribution obtained from dielectric ac data (5 Hz-300 MHz, 100 K-300 K) with the results of a thermally stimulated depolarization currents sampling technique. The contour line of (Formula presented) is shown to follow the compensation law.