• The variable –sex– is string, but it should be encoded to numeric.
  
  
  
• The variables –education– and –married– are numeric but do not have value
  labels, yet. Label the values of the two variables according to those given below
  in the Appendix.
  
  
  
  
  
• The variable –education– has too many categories; recode the variable, so that
  it has fewer, meaningful categories. Also, the variable –income– has missings,
  they should be recoded to 0.
  
  
  
• How does wage income vary by age, sex, and education
  
  
  
  –married–:
  1 - married
  2 - not married
  –education–: 1 - tertiary
  2 - unfinished tertiary
  3 - special secondary
  4 - secondary
  5 - 7 years of schooling 6 - primary
  7 - can read and write 8 - can read
  9 - illiterate
  10 - child aged 0-8 99 - missing value