Annual earnings in $
Natural logarithm of earnings
= 1 if earnings > 25000 and = 0 otherwise
Age in year
Age squared
= 1 if age >= 50 and = 0 otherwise
Educational attainment: years of schooling
Education squared
?
Education times Age
1 if self-employed, 0 otherwise
1 if work for wages in private sector, otherwise
1 if work for wages in govt sector
Usual hours worked per week
Natural logarithm of hours