Years of schooling
number of doctor visits
Age in years / 10
Income in $ / 1000
= 1 if female
= 1 if black
= 1 if hispanic
= 1 if married
= 1 if Northeast
= 1 if Midwest
= 1 if South
= 1 if metropolitan statistical area
Size of firm/100
= 1 if very good health
= 1 if good health
= 1 if physical limitation
= 1 if fair or poor health
= age x age
= 1 if year 1997
= 1 if year 1998
= 1 if year 1999
= 1 if year 2000
= 1 if year 2001
= 1 if year 2003
Family size
= 1 if an injury
= 1 if private insurance
= 1 if a chronic condition