The fraction of stars with XHIP literature radial velocities which are contained in the radial-velocity interval [m − R,m + R]  as function of R, with m = −2.21 km s^-1 the mean v_r for the Gaussian criterion and m = −2.00 km s^-1 the median v_r for the robust criterion (Sects. 2.2 and 6.2). For the Gaussian criterion, we represent the histogram of literature radial velocities by a Gauss with standard deviation σ = 22.44 km s^-1 (Fig. 1). The dashed lines represent the classical limits 1σ = 68.27%, 2σ = 95.45%, and 3σ = 99.73%. The fraction of stars with the robust criterion builds up more slowly as a result of the non-Gaussian broad wings as well as outliers representing halo and runaway stars. Since the Gaussian criterion ignores these features, it returns biased results for stars without literature radial velocity (see Sect. 6.3).