Stellar relative Stokes parameters (q, u) versus the distance modulus for the full sample. The q_V and u_V (in the Equatorial coordinate system) are shown by green circles and blue diamonds, respectively. The vertical error bars indicate the uncertainties (noise and systematic) on the Stokes parameters and the horizontal error bars represent the uncertainties on the star distance modulus converted from the 1σ parallax uncertainties. Outliers identified from the iterative sigma-clipping approach in groups of nearest neighbors are highlighted with red-filled circles for q and purple-filled squares for u. To facilitate the visual clarity of the plot we restrict the range of (q, u) and µ values. Ten stars have µ < 5 and 30 stars have µ > 14.