  Due to the specificity of China's dualistic household registration system and
the differences in the rights and interests attached to it, household
registration is prevalent as a control variable in the empirical evidence. In
the context of family planning policies, this paper proposes to use family size
and number of children as instrumental variables for household registration,
and discusses qualitatively and statistically verifies their relevance and
exogeneity, while empirically analyzing the impact of the household
registration system on citizenship of the mobile population. After controlling
for city, individual control variables and fixed effects, the following
conclusions are drawn: family size and number of children pass the
over-identification test when used as instrumental variables for household
registration; non-agricultural households have about 20.2% lower settlement
intentions and 7.28% lower employment levels in inflow cities than agricultural
households; the mechanism of the effect of the nature of household registration
on employment still holds for the non-mobile population group.
