{
  "age": "measured in years",
  "education": "measured in years",
  "black": "indicating race (1 if black, 0 otherwise)",
  "hispanic": "indicating race (1 if Hispanic, 0 otherwise)",
  "married": "indicating marital status (1 if married, 0 otherwise)",
  "nodegree": "indicating high school diploma (1 if no degree, 0 otherwise)",
  "re75": "real earnings in 1975",
}
