Success rate S of our method in recovering the correct shape of a DM halo as a function of the size of the HVS observed sample, for a spherical DM halo (q_z = 1.0; black dots) and for two spheroidal DM halos axisymmetric about the z axis with q_z = 1.1 (green dots) and q_z = 1.4 (red dots). The sample size reported on the x axis is the average size of the 5000 HVS observed samples used to estimate the success rate in the spherical DM halo scenario. S is shown for sample sizes of 100% (N ≃ 800 stars), 50% (N ≃ 400 stars), 25% (N ≃ 200 stars), 10% (N ≃ 80 stars), and 5% (N ≃ 40 stars) of the original sample size.