The data are taken from Weisberg (1985).  The first column is simply
the case number.  The subsequent columns are:

    SEX = male or female
    WT2 = weight at age 2 (kg)
    HT2 = height at age 2 (cm)
    WT9 = weight at age 9
    HT9 = height at age 9
    LG9 = leg circumference at age 9 (cm)
    ST9 = a composite measure of strength at age 9 (high values =
   	  stronger)
   WT18 = weight at age 18
   HT18 = height at age 18
   LG18 = leg circumference at age 18 (cm)
   ST18 = strength at age 18
   SOMA = somatotype, a seven-point scale, as a measure of fatness
          (1=slender, 7=fat), determined using a photograph taken
          at age 18.}