dcode: district code
bcode: building code
math4: percent satisfactory, 4th grade math
read4: percent satisfactory, 4th grade reading
enroll: school enrollment
exppp: expenditures per pupil, $
free: percent eligible, free lunch
reduced: percent eligible, reduced lunch
lunch: free + reduced
medinc: zipcode median family, $ (1999)
totchild: # of children (in zipcode)
married: # of children in married-couple families
single: # of children not in married-couple families
pctsgle: percent of children not in married-couple families
zipcode: school zipcode
lenroll: log(enroll)
lexppp: log(exppp)
lmedinc: log(medinc)