Econometric Model
We empirically examine the importance of
economic contextual factors such as food
prices and availability and individual-level
factors on adult BMI. The empirical model
is based on an economic framework where
individuals engage in behaviors related to
work, leisure, and home production; they produce
and demand health and weight; and
finally, they also consume food that directly
and indirectly (through changes in weight
and health) impacts utility (Cawley 2004).
Weight outcomes depend on marginal costs
and benefits related to behaviors such as
food consumption. Higher costs of healthful
foods through direct monetary prices (i.e., fruit
and vegetable prices) and limited access (i.e.,
lower supermarket availability) are expected
to increase weight outcomes, whereas lower
costs of unhealthy energy-dense food (i.e., fastfood
prices) and increased access (i.e., greater
availability of fast-food restaurants or convenience
stores) are expected to raise weight.Our
empirical model examines the importance of
the direct monetary prices of fruits and vegetables
and fast food. In addition, we proxy the opportunity cost of the time spent acquiring
the food and the preparation and clean-up
time by examining measures of availability
of restaurants (including full-service and fastfood
restaurants) and food stores (including
supermarkets, grocery stores, and convenience
stores).We also include neighborhood median
household income and urbanization indicators
in our models to help further control for
potential unobserved local area heterogeneity.
We estimate a reduced-form empirical
model of adult BMI as:
(1) BMIist =β0 + β1PRICESst + β2FSTst
+ β3RESst + β4Xist
+ β5Dt + εist