OLS			IV: SNAP+ SNAP2+SNAP policy index
Variables	Coeff. of WIC participation	S.E	P-value	Coeff. of WIC participation	S.E	P-value	Identification test‡
ALL	−0.064	0.007	< 0.001	0.018	0.318	0.956	UWO
Boy	−0.072	0.009	< 0.001	0.374	0.386	0.332	O
Girl	−0.057	0.009	< 0.001	−0.266	0.443	0.549	UWO
Non-H White	−0.087	0.008	< 0.001	−0.403	0.925	0.663	O
Non-H Black	−0.069	0.019	<0.001	0.365	0.659	0.580	UO
Hispanic	−0.025	0.012	0.030	0.590	0.287	0.040	O
Other	−0.035	0.017	0.047	−0.108	0.458	0.814	UO

^†Controlling state dummy, sex, race/ethnicity, education, child’s age, maternal age, maternal marital status, number of people in the household, interview language, birth year, TANF/Temporary Assistance for Needy Families enrollment rate (# of enrolled participants/# of state population), CHIP/Children’s Health Insurance Program enrollment rate (# of enrolled children/# of children 18 or under in the state), and state unemployment rate. IV Variables including SNAP enrollment rates (SNAP, # of SNAP participants in that year/# of state population in that year), square of SNAP enrollment rates (SNAP²), and SNAP policy index.

^‡U means the under-identification test P < 0.05. Stock–Yogo tabulations based on the Cragg–Donald statistic were used for the weak identification test; W means the F statistic of the weak identification test > 10% maximal IV relative bias or > 10% maximal IV size. O means over-identification test > 0.05. (O could not be tested in the first stage).