Comparison between the stellar parameters obtained using spectra from different instruments, with respect to the ones obtained with HARPS. The y-axis for each plot corresponds to the difference between the parameters. Blue dots correspond to FEROS data, red triangles to UVES data, and green diamonds to HIRES data. For each panel, the right-hand plot corresponds to the distribution of the values, and solid line to the Gaussian distribution adjusted to each histogram. The black points in the bottom right of each plot represents the average uncertainty in the points.