Relative errors on the estimated parameters ﹩\delta p/p﹩, defined as ﹩({p}_{\mathrm{fit}}-{p}_{\mathrm{in}})/{p}_{\mathrm{in}}﹩. Each row shows ﹩\delta p/p﹩ for the maximum circular velocity ﹩{V}_{\mathrm{max}}﹩, the size ﹩{R}_{1/2}﹩, the PA, and inclindation i from top to bottom, respectively. The crosses, squares, and circles represent the three subsamples with sizes ∼2.5, 5, and 7.5 kpc, respectively (Table 3). The relative errors for the morphological parameters (size, PA, inclination) are binned. (a) Relative errors as a function of central SB ﹩{\mathrm{SB}}_{1/2,\mathrm{obs}}﹩ in erg s⁻¹ cm⁻² arcsec⁻². (b) Relative error as a function of central SB ﹩{\mathrm{SB}}_{1/2,\mathrm{obs}}﹩ times ﹩{({R}_{1/2}/{R}_{\mathrm{PSF}})}^{\alpha }﹩, where ﹩{R}_{1/2}﹩ is the galaxy intrinsic half-light radius and ﹩{R}_{\mathrm{PSF}}﹩ the PSF half-light radius. We found, empirically (see text), that α is approximately 0.8, 1.2, and 1.4 for the size, PA, and inclination parameter, respectively. These values are close to the expectation of ﹩-1.0﹩ of Equation (10) (gray lines) derived for morphological parameters in imaging data by Refregier et al. (2012). The relative error in ﹩{V}_{\mathrm{max}}﹩ does not follow the expected relation and is subject to strong systematics for the smallest and largest mock galaxies (crosses). This is due to ﹩{V}_{\mathrm{max}}﹩ being constrained in the outer parts of the galaxy, where the S/N is thus not sufficient for the compact galaxies or where the mock cube is too small for the largest galaxies.