Convolution values obtained for the sample stars against surface gravities (upper panel) and metallicity (lower panel). Red squares indicate spectra with a low mean fiber number (< 100), blue points indicate spectra with a high mean fiber number (> 200), and black triangles indicate the others. The continuous line corresponds to the macroturbulence relation adopted in APOGEE DR14 quadratically summed with an average resolution of 13.3 km s⁻¹ (R ∼ 22 500).