Comparison among the radial velocity estimates. On the x-axes we plot the radial velocities measured with the second method, which fits two Gaussian functions and a quadratic polynomial to the line cores and wings. The y-axes display the difference between the Gaussian fit and the first method that uses the spectral templates to fit the line wings, respectively for the Koester and Tremblay models on the left and right panels. The left panels compare the Hα+Hβ measurements, while the right panels show the same comparison for the Hα line. The colors and shapes of the symbols are the same as in Fig. 3.