NLTE changes of the emergent Stokes V profiles in the blue and red wings of the Si i 10 827 Å line versus the vertical magnetic field component B_Z. Left: results for the blue wing at Δλ = −0.08 Å. Right: results for the right wing at Δλ = 0.10 Å. The given Δλ points correspond to the mean wavelength positions of the Stokes V peaks in the blue and red wings of this line (see the top panel of Fig. 3). The B_Z values are measured at the heights H_Δλ(NLTE), where the NLTE optical depth at a given wavelength is equal to unity. Black circles and vertical lines indicate averages and error bars, correspondingly, over bins with 50 surface points. The NLTE Stokes parameters are calculated using the simplest Si i model with six bb transitions and assuming S_H = 0.1.