Average values of the normalized SCF over the Heiles cloud 2 map (only spectra with ﹩Q> 2﹩ are used), as a function of the velocity window, W, used in the computation of the SCF. The larger the velocity window, the smaller the values of the SCF of the spectra with randomized positions, because more noise enters the comparison of neighboring spectra. This does not happen for the SCF of the original map, because the effect of noise is appropriately corrected for. The definition of σ is the same as in Fig. 3.