The use of an IV-probit model is preferred, both because it solves the problem of the high occurrence of zeros, and because it is coherent with the Heckman results. Tables 2 and 3 present the estimated effect of SIGI in both origin and destination countries on female migration flows. The OLS estimates are provided in Table 2 column (1), Table 2 columns (2) and (3) report the estimates using the two-step Heckman approach and Table 3 those using instrumental variable.