Ytij, or healthy behavior engagement for individual i at age t in school j is a function of an individual-specific baseline level of healthy behaviors at age 13, p0ij, plus the mean growth rate p1ij for child i in school j. The individualspecific age-13 level of health behavior engagement, p0ij, is a function of school j mean age-13 level of health behavior engagement. This school mean is a function of the grand mean level of healthy behaviors for all individuals across all schools, g000. The rate of healthy behavior change p1ij for individual i at school j is a function of the average growth rate of school j for individual i (b10j), and the
average school growth rate is a function of the grand mean growth rate g100, or the average growth rate for all individuals at all ages across all schools. Variance components at each level estimate model variance at age 13 remaining at the within-individual (etij), within
school (r0ij) and between school (m00j) levels and also at the slope (r1ij and m10j).