their state of birth for the 1990 census, had essentially no effect on parameter estimates (See Supplemental Table 1). Likewise, using state-of-residence, rather than state-of-birth, to estimate MLDA exposure had little impact (See Supplemental Table 2). Inclusion of educational attainment or linear state-by-year interactions (i.e., state-specific secular trends) as additional covariates had essentially no effect on the parameter estimates (results not shown).
