Ratio of the number of HII regions of luminosity L(Hα) > 10³⁷ erg s⁻¹ (for those galaxies with at least 20 HII regions) located within and outside the r-band effective radius, as a function of the HI-deficiency parameter. Triangles are lower limits on the HI-deficiency parameter (when pointing to the right) or on the N(HII)_in/N(HII)_out (when pointing to the top). These latter indicate those objects where HII regions have been detected only within the r-band effective radius (N(HII)_out = 0). Symbols are colour-coded as in Fig. 1.