age, a numeric variable containing the interviewee's age in
years;
race, a factor with 20 levels denoting various racial/ethnic
origins;
gender, a factor with levels "Male" and "Female".
grade90, a factor containing the highest completed school
grade from "3RD GRADE" to "8TH YR COL OR MORE", with 18 levels;
income06, a numeric variable, income in 2006 in 10000-USD
units;
income96, a numeric variable, income in 1996 in 10000-USD
units;
income90, a numeric variable, income in 1990 in 10000-USD
units;
partner, a factor encoding whether the interviewee has a
partner, with levels "No" and "Yes";
height, a numeric variable, the height of the interviewee;
weight, a numeric variable, the weight of the interviewee;
famsize, a numeric variable, the number of family members;
genhealth, a factor with levels "Excellent",
"Very Good", "Good", "Fair", "Poor" encoding
the general health status of the interviewee;
illegalact, a numeric variable containing the number of illegal
acts committed by the interviewee;
charged, a numeric variable containing the number of illegal
acts for which the interviewee has been charged;
jobsnum90, a numeric value, the number of different jobs ever
reported;
afqt89, a numeric value, the percentile score of the "Profiles,
Armed Forces Qualification Test" (AFQT);
typejob90, a factor with 13 levels encoding different job
types;
jobtrain90, a factor with levels "No" and "Yes"
encoding whether the job was classified as training.