The distribution of population characteristics

Mean values of BMI from age 7 to 33 years old in females by age at menarche were digitized from Fig. 1 in Power et al. (1997). A linear regression was performed for BMI and age at menarche. Females at 7 years old had Microcystin-LR following relationship for BMI with their age at menarche: BMI at 7 years = 20.265 − 0.3488 · Age at menarche. Females at 33 years old had the following relationship for BMI with their age at menarche: BMI at 33 years = 36.937 − 0.9722 · Age at menarche. So we have: a) (BMI for an systematics individual at 7 years − median BMI at 7 years) = − 0.3488 · (Age at menarche for an individual − median age at menarche); b) (BMI for an individual at 33 years − median BMI at 33 years) = − 0.9722 · (Age at menarche for an individual − median age at menarche).