In our following specifications, we add variables that are arguably
increasingly endogenous in that they reflect in part choices
made now and in the past by respondents or their parents. First we
add two variables proxying childhood health. There is now a large
literature regarding early life origins of later life health (e.g. Barker,
1994; Gluckman and Hanson, 2005; Zhang et al., 2010). The coefficients
of current SES may represent in part omitted factors such
as influences from childhood health, so we include these both to
examine those coefficients directly and to see how the coefficients
change of current SES covariates. The first childhood health covariate
is derived from a general health measure of child health before
age 16, on scale of excellent, very good, good, fair, and poor. This is
the same variable used in HRS andwas used by Smith et al. (2012) to
examine childhood health-later life health correlations using the
CHARLS pilot survey.