Relative spinal bone mineral density measurements on 261 North
American adolescents.  Each value is the difference in spnbmd
taken on two consecutive visits, divided by the average. The age is
the average age over the two visits.

Variables:

idnum:		identifies the child, and hence the repeat measurements
age:		average age of child when measurements were taken
gender:		male or female
spnbmd:		Relative Spinal bone mineral density measurement

If you use these data in a publication, please acknowledge the
original source:

Bachrach LK, Hastie T, Wang M-C, Narasimhan B, Marcus R. Bone Mineral
Acquisition in Healthy Asian, Hispanic, Black and Caucasian Youth. A
Longitudinal Study. J Clin Endocrinol Metab (1999) 84, 4702-12.